Emilia felt weighed down.

She couldn't be sure if it was her own worries causing it or if the final stretch of road toward the Doors of Death had that effect.

She was practicing her invisibility every few paces, finding it easy to maintain with all the darkness around them. Percy and Annabeth looked terrible, arms resembling bleached leather pulled over sticks, skeletal legs seemingly ready to dissolve into smoke at any given moment. Under their feet, the ground glistened a nauseating purple, pulsing with webs of veins.

The closer they got to the Doors, the more she saw of the army. In the dim red light, the horizon was lined with bodies. Flocks of winged arai, tribes of lumbering Cyclopes, clusters of floating evil spirits, maybe tens of thousands of monsters milling restlessly, pressing against one another, growling and fighting for space.

Bob led them toward the edge of the army. He made no effort to hide, not that it would have done any good, given he was ten feet tall and glowed silver. Percy and Annabeth walked directly behind him while Emilia remained at his side, completely invisible. Small Bob purred seismically over his shoulder, sniffing at the air where Emilia stood but not daring to jump out at what he couldn't see.

"Bob," came Annabeth's voice. "If we're invisible... how can you see us? I mean, you're technically, you know..."

"Yes," said Bob. "But we are friends."

Annabeth hesitated, looking to where she knew Emilia was walking. "Emilia, you said Nyx and Eris could see us."

"They could," said Emilia. "Maybe because you were in the Mansion of Night... all truths are revealed there. Here, I imagine you choose who sees you. We're not in my grandmother's domain anymore. We should be safe. Stay together and let me handle things."

They plunged into the crowd. A few feet away, a group of empousai tore into the carcass of a gryphon while other gryphons flew around them, squawking in outrage. A six-armed Earthborn and a Laistrygonian giant pummeled each other with rocks, though there wasn't any clear indication that they were just playing around... it could have been a real fight. A dark wisp of smoke– perhaps an eidolon– seeped into a Cyclops, made the monster hit himself in the face, then drifted off to possess another victim.

A stone's throw away, a familiar man in a cowboy outfit was cracking a whip at some fire-breathing horses. The wrangler wore a Stetson hat on his greasy hair, an extra-large set of jeans, and a pair of black leather boots. His upper body was split into three different chests, each one dressed in a different-color Western shirt.

"Geryon," muttered Emilia. "Chrysaor's weird ass son."

She could tell it was starting to affect Annabeth and Percy. To see their old enemies, to feel themselves having to hide here, not having been guaranteed safety since they first arrived in Tartarus. Emilia worried about what Nyx had said, how her survival was sure but theirs wasn't.

How was she going to get them out of here? If she had to sacrifice anything to get them out, how would she escape?

Somewhere in front of them, a deep voice broke their self-imposed anxious silence. "IAPETUS!"

The hairs on the back of Emilia's neck stood as a Titan strode toward them, casually kicking lesser monsters out of the way. He was roughly the same height as Bob, with elaborate Stygian iron armor, a single diamond blazing in the center of his breastplate. His eyes were blue-white, like core samples from a glacier, and just as cold. His hair was the same color, cut military style. A battle helmet shaped like a bear's head was tucked under his arm. From his belt hung a sword the size of a surfboard.

Despite his battle scars, the Titan's face was handsome. He reminded Emilia of Apollo and Artemis, their eyes and smiles too similar to this Titan, their grandfather.

The Titan stopped in front of Bob. He clapped him on the shoulder. "Iapetus! Don't tell me you don't recognize your own brother!"

"No!" Bob agreed nervously as Emilia fought the urge to whisper what he needed to know. "I won't tell you that."

The other Titan threw his head back and laughed. "I heard you were thrown into the Lethe. Must've been terrible! We all knew you would heal eventually. It's Koios! Koios!"

"Titan of the North!" Emilia dared to hissed, voice only just masked by Small Bob's unnaturally loud purrs.

"Of course!" said Bob, hearing her. "Koios, Titan of the North." They laughed together and took turns hitting each other in the arm. Apparently miffed by all the jostling, Small Bob stopped purring, and crawled onto Bob's head, making a nest in the Titan's silver hair.

"Poor old Iapetus," said Koios. "They must have laid you low indeed. Look at you! A broom? A servant's uniform? A cat in your hair? Truly, Hades must pay for these insults. Who was that demigod who took your memory? Bah! We must rip him to pieces, you and I, eh?"

Bob mustered an awkward laugh, then swallowed. "Yes, indeed. Rip him to pieces."

Koios clearly hadn't noticed the presence of the demigods. "Ah, it's good to see you..." He drummed his fingers on his bear's-head helmet. "You remember what fun we had in the old days?"

"Of course!" chirped Bob, though he obviously remembered nothing. "When we, uh..."

"Holding down our father, Ouranos."

"Yes! We loved wrestling with Dad..."

Emilia had to fight the urge to smack herself in the face as Koios made a face and corrected, "We restrained him."

"That's what I meant!"

"While Kronos cut him to pieces with his scythe."

"Yes." Bob looked mildly ill as he forced a laugh. "What fun."

"You grabbed Father's right foot, as I recall. And Ouranos kicked you in the face as he struggled. How we used to tease you about that!"

"Silly me," agreed Bob.

"Sadly, our brother Kronos was dissolved by those impudent demigods." Koios heaved a sigh. "Every preventative measure he took, and none of it prevailed. Bits and pieces of his essence remain, but nothing you could put together again. I suppose some injuries even Tartarus cannot heal. But the rest of us have another chance to shine, eh?" He leaned forward conspiratorially. "These giants may think they will rule. Let them be our shock troops and destroy the Olympians– all well and good. But once the Earth Mother is awake, she will remember that we are her eldest children. Mark my words. The Titans will yet rule the cosmos."

Emilia doubted Gaea would do such a thing. Bob hummed, "The giants may not like that."

"Spit on what they like. They've already passed through the Doors of Death, anyway, back to the mortal one. Polybotes was the last one, not half an hour ago, still grumbling about missing his prey. Apparently some demigods he was after got swallowed by Nyx. Never see them again, I wager!"

Emilia glanced back at Annabeth and Percy, their eyes widened in alarm. They were in a bit less danger now, but the same could not be said for their friends. Their enemies were still alive– all earlier fights no longer mattered.

"Well!" Koios drew his massive sword, which radiated a deep cold. "I must be off. Leto should have regenerated by now. I will convince her to fight."

"Of course," murmured Bob. "Leto."

Koios laughed. "You've forgotten my daughter, as well? I suppose it's been too long since you've seen her. The peaceful ones like her always take the longest to re-form. This time, though, I'm sure Leto will fight for vengeance. The way Zeus treated her, after she bore him those fine twins? Outrageous!" He chest-bumped Bob, almost knocking Small Bob off his head. "Well! I'll see you in the mortal world! Oh, and our two other brothers are guarding this side of the Doors, so you'll see them soon enough!"

"I will?"

"Count on it!" Koios lumbered off. Before the crowd of monsters could fill the empty space, Percy motioned for Bob to lean in, "You okay, big guy?"

Bob frowned. "I do not know. In all this–" he gestured around them, "what is the meaning of okay?"

A good point. "Let's just keep moving," insisted Emilia. "We'll deal with the Titans at the doors when we arrive. At least we don't have to deal with Koios now... he was a great strategist, we wouldn't be able to outsmart him here. Even Kronos regarded him with great esteem."

Percy still seemed worried about the fact Koios had been present at all. "Do you remember Koios?" he asked Bob gently. "All that stuff he was talking about?"

Bob gripped his broom. "When he told it, I remembered. He handed me my past like... like a spear. But I do not know if I should take it. Is it still mine, if I do not want it?"

"No," said Annabeth firmly. "Bob, you're different now. You're better."

Emilia shook her head. "It isn't just that. Bob... I can't claim to have gone through anything like you did, but I had a moment where I could choose my path. Better... or worse. Your past will always be yours. Whatever you start to remember... will remain true. Sometimes it's good for us to recall what used to be, even if it hurts, even if it reminds us of a time when we weren't who we are now. But you can decide what you do with it. Will you accept it, learn from it, and choose who you prefer to be, based on how you feel most comfortable, most free? Or will you let the gaps be filled in and go back to the way things were? Which makes you happier?"

Bob considered it. "I like having friends. I like not being like Kronos, who hurt you all. I like being... Bob."

"That's great. You can always be Bob, as much as you'd like. Acknowledge what you like, disregard what you don't. You decide how your future goes. Only you can finish writing the story that was started for you."

"Future..." Bob mused. "That is a mortal concept. I am not meant to change, Emilia Friend. We are the same... forever."

"If you were the same," said Percy, "we would be dead already. Maybe we weren't meant to be friends, but we are. You've been the best friend we could ask for."

Bob's silver eyes looked darker than usual. He held out his hand, and Small Bob the kitten jumped into it. The Titan rose to his full height. "Let us go, then, friends. Not much farther."

The purplish ground beneath their feet was constantly pulsing, just as a heart always did. The terrain looked flat from a distance, but up close it was made of folds and ridges that got harder to navigate the farther they walked. Gnarled lumps of red arteries and blue veins gave them some footholds when they had to climb, but they were moving slowly– too slowly.

The monsters remained all around them. Packs of hellhounds– Emilia tried not to think of them as being Nyx's children, too, because then it made her remember that Mrs. O'Leary was technically her aunt– prowled the plains, baying and snarling and attacking any monster that dropped its guard. Arai wheeled overhead on leathery wings, making ghastly dark silhouettes in the poison clouds.

Percy stumbled. He placed his hand against the ground, up against a red artery. "There's water in here. Actual water."

Bob grunted. "One of the five rivers. His blood."

"His blood?" Annabeth stepped away from the nearest clump of veins. "I knew the Underworld rivers all emptied into Tartarus, but—"

"Yes," agreed Bob. "They all flow through his heart."

Percy traced his hand across a web of capillaries. "Don't think about it, it'll just make us more paranoid," recommended Emilia, now also tiptoeing around the veins. "Hurry, we're almost there..."

Ahead of them, jagged streaks of darkness tore through the air—like lightning, except pure black. "The Doors," said Bob. "Must be a large group going through."

Emilia wasn't sure how much time had passed, if their friends would even be on the other side of the Doors when they emerged. But if they were, how were they going to fight off all these waves of monsters coming at them, especially with the giants out there waiting for them?

"Do all the monsters go through the House of Hades?" asked Percy "How big is that place?"

Bob shrugged. "Perhaps they are sent elsewhere when they step through. The House of Hades is in the earth, yes? That is Gaea's realm. She could send her minions wherever she wishes."

"Let's not focus on that," insisted Emilia, mouth feeling dry. She had the advantage, she could protect them all, but she couldn't be in two places at once.

Annabeth was still overthinking. "If Gaea has that much power, couldn't she control where we end up?"

Percy and Emilia both gave her a significant look, wishing she wasn't so smart. Bob scratched his chin. "You are not monsters. It may be different for you."

Bob helped them over the top of another ridge. Suddenly the Doors of Death were in plain view—a freestanding rectangle of darkness at the top of the next heart-muscle hill, about a quarter mile away, surrounded by a horde of monsters so thick that they could've walked on their heads all the way across.

The Doors were still too far away to make out much detail, but the Titans flanking either side were familiar enough. The one on the left wore shining golden armor that shimmered with heat.

"Hyperion," muttered Percy. "That guy just won't stay dead."

The one on the right wore dark-blue armor, with ram's horns curling from the sides of his helmet. Krios, the Titan that Jason had killed in the battle for Mount Tam. It was different to see them together again, considering the last time this happened, Emilia had been a very different person. It must have felt way worse for Bob.

"Bob's other brothers," said Annabeth. The Death Mist shimmered around her, temporarily turning her face into a grinning skull. "Bob, if you have to fight them, can you?"

Emilia wished she hadn't asked that of him. Bob hefted his broom, like he was ready for a messy cleaning job. "We must hurry," he said, naturally avoiding an answer. How could they expect him to make that choice right now? "Follow me."

They were fifty feet from the doors when Annabeth froze. "Oh my gods. They're the same."

Framed in Stygian iron, the magical portal was a set of elevator doors— two panels of silver and black etched with art deco designs. Except for the fact that the colors were inverted, they looked exactly like the elevators in the Empire State Building, the entrance to Olympus.

Emilia could see frost spreading from the base of the Doors, a purplish glow in the air around them, and chains that held them fast. Cords of black iron ran down either side of the frame, like rigging lines on a suspension bridge. They were tethered to hooks embedded in the fleshy ground. The two Titans, Krios and Hyperion, stood guard at the anchor points.

The entire frame shuddered. Black lightning flashed into the sky. The chains shook, and the Titans planted their feet on the hooks to keep them secure. The Doors slid open, revealing the gilded interior of an elevator car. Hyperion beckoned a dozen Cyclopes into the elevator. They shouldn't have been able to fit inside those human-sized doors, but as they got close, their bodies distorted and shrank, the Doors of Death sucking them inside. Krios jabbed his thumb against the up button on the elevator's right side. The Doors slid closed.

"You must understand how it works," muttered Bob. He addressed the kitten in his palm, maybe so the other monsters wouldn't wonder who he was talking to. "Each time the Doors open, they try to teleport to a new location. Thanatos made them this way, so only he could find them. But now they are chained. The Doors cannot relocate."

"We have to cut the chains," whispered Emilia.

"Our camouflage," said Percy. "Will it disappear if we do something aggressive, like cutting the chains?"

"I do not know," Bob told his kitten. Small Bob chirped with great interest.

"Bob, you'll have to distract them," decided Annabeth. "Emilia, Percy, and I will sneak around the two Titans and cut the chains from behind."

"Yes, fine," Bob said. "But that is only one problem. Once you are inside the Doors, someone must stay outside to push the button and defend it."

Percy was confused. "Uh...defend the button?"

Bob nodded, scratching his kitten under the chin. "Someone must keep pressing the UP button for twelve minutes, or the journey will not finish."

"I can try to make it happen with shadows," said Emilia, though she sounded doubtful. She wouldn't be as strong outside of Tartarus, she might no longer have that same control over the shadows. Did it mean one of them was going to have to stay behind?

Annabeth held out her hand. "What do you mean the journey won't finish? What happens to the passengers?"

Bob didn't answer, expression pained. Percy decided to move on, "If we do push the button for twelve minutes and the chains are cut—"

"The Doors should reset," said Bob. "That is what they are supposed to do. They will disappear from Tartarus. They will appear somewhere else, where Gaea cannot use them."

"Thanatos can reclaim them," said Annabeth. "Death goes back to normal, and the monsters lose their shortcut to the mortal world."

Percy exhaled. "Easy-peasy. Except for... well, everything." Small Bob purred.

"I will push the button," volunteered Bob.

Percy shook his head. "Bob, we can't ask you to do that. You want to go through the Doors too. You want to see the sky again, and the stars, and—"

"I would like that," agreed Bob. "But someone must push the button. And once the chains are cut... my brethren will fight to stop your passage. They will not want the Doors to disappear."

Emilia's hands trembled. "No. No, we can't leave you to do that. Bob, I will stay with you."

"Emilia!" said Annabeth in disbelief. "No– no, what are you saying?"

"I'm safe here," she said, trying her best to sound like she believed it. "The monsters, they never tried to hurt me. I can help Bob hold them off. And then... Then, before the Doors fully disappear, I can pray to Thanatos. He is my uncle. He'll listen, he'll let us out."

"You don't know that!"

"No, I don't, but I know that we're not leaving Bob and Small Bob. Listen to me..." She knew they couldn't see her, but placed her hands on their shoulders all the same. "I have the advantage here. I intended to come here alone when we first realized what needed to be done... I know I will be fine. Don't argue. Just let me try this. Please. Look at me, I'm perfectly fine– strong, nourished. You two are still slowly dying. You have to get out of here."

Annabeth stared in her direction, perhaps rethinking everything Emilia had told them about the Mansion of Night. Emilia found herself thinking of it, too. Did she want a chance to stay? Did she crave being here just a bit longer, to have another conversation with her mother before she had to go back? To learn more about herself, to maximize what she could do against Gaea?

She tried to imagine Hylla's face as she looked at Annabeth and realized it didn't make her want to abandon this plan. Hylla and Emilia were the same– they respected selflessness in battle, they understood taking risks, they would both sacrifice themselves for those they cared about without a moment of hesitation. Emilia wouldn't forgive herself if they left Bob behind to die. She had promised Hylla she'd make it back to her and she would. But that included her honor and Emilia would not abandon it here. She could still cling to the hope of seeing Hylla again. Her hope would live as long as her friends did.

Her friends might not understand it but she knew that Hylla would. Pollux would. Will would. It mattered to Emilia. She'd once thought her own beliefs and feelings didn't matter, and now she knew different.

She trusted herself to succeed. She trusted her friends to do what needed to be done.

"Emilia," said Percy quietly. "Are you sure?"

"Yes," she insisted. "I am sure. Let's do this."

Percy crept to the right as Annabeth sneaked toward the left– she insisted that if Percy got too close to Hyperion, he'd sense him. Bob lumbered forward, entering the Titans' field of vision. "IAPETUS!" bellowed Hyperion. "Well, well. I thought you were hiding under a cleaning bucket somewhere."

Bob scowled. "I was not hiding. Hyperion and Krios. I remember you both."

Emilia remained glued to his side, a path clear for the others given the lesser monsters kept a respectful distance from the Titans. She watched their surroundings carefully, doing her best to create a small shield of darkness so that the monsters wouldn't catch sight of any weapons being moved around, either.

"Do you, Iapetus?" The golden Titan laughed, glancing at Krios to share the joke. "Well, that's good to know! I heard Percy Jackson turned you into a brainwashed scullery maid. What did he rename you... Betty?"

"Bob," snarled Bob.

"Well, it's about time you showed up, Bob. Krios and I have been stuck here for weeks—"

"Hours," corrected Krios, his voice a deep rumble inside his helmet.

"Whatever!" said Hyperion. "It's boring work, guarding these doors, shuffling monsters through at Gaea's orders." Emilia rolled her eyes as he continued to sneer about the different groups going in. He seemed to think he was worth more. She wished she could be visible enough to signal to Percy and Annabeth. Right now, she was guarding them and doing nothing more. Only when the chains broke could she surge forward to hold the button while Bob distracted his brothers.

She saw Riptide growing to its full length behind Krios, who didn't sense Percy at all, his attention firmly fixed on Bob, who had just leveled the point of his spear at Hyperion's chest after a comment his brother made about his nickname and how much he 'changed.'

"I can still pierce," Bob was saying, his voice low and even. "You brag too much, Hyperion. You are bright and fiery, but Percy Jackson defeated you anyway. I hear you became a nice tree in Central Park."

Hyperion's eyes smoldered. "Careful, brother."

"At least a janitor's work is honest," said Bob. "I clean up after others. I leave the palace better than I found it. But you...you do not care what messes you make. You followed Kronos blindly. Now you take orders from Gaea."

"She is our mother!" bellowed Hyperion.

"She did not wake for our war on Olympus," recalled Bob. "She favors her second brood, the giants."

Krios grunted. "That's true enough. The children of the pit."

"Both of you hold your tongues!" Hyperion's voice was tinged with fear. "You never know when he is listening."

The elevator dinged. All three Titans jumped. Emilia was getting anxious with them talking about Tartarus, with them arguing. It was a different side of Bob, one that worked well for their mission, but she worried he could get distracted defending himself from all the rude jabs.

Annabeth raised her drakon-bone sword over the base of the chains. She held up three fingers to Percy, ready to count down. They had to cut the chains before the next group tried to take the elevator, but they also had to make sure the Titans were as distracted as possible.

Hyperion muttered a curse at the group, which didn't seem to have what they needed to board. "Just wonderful. This will completely mess up our schedule." He sneered at Bob. "Make your choice, brother. Fight us or help us. I don't have time for your lectures."

Bob glanced at Annabeth and Percy, then raised his spear. "Very well. I will take guard duty. Which of you wants a break first?"

"Me, of course," said Hyperion.

"Me!" snapped Krios. "I've been holding that button so long my thumb is going to fall off."

"I've been standing here longer," grumbled Hyperion. "You two guard the Doors while I go up to the mortal world. I have some Greek heroes to wreak vengeance upon!"

"Oh, no!" complained Krios "That Roman boy is on his way to Epirus— the one who killed me on Mount Othrys. Got lucky, he did. Now it's my turn."

(Emilia so desperately wished that she could whisper just to Bob that he should make up some sort of lie about being able to guard and hold the button at the same time. He could say that Small Bob could fly and hold the button– she'd grab the cat and make it seem so, if she had to.)

"Bah!" Hyperion drew his sword. "I'll gut you first, Ram-head!"

Krios raised his own blade. "You can try, but I won't be stuck in this stinking pit any longer!"

Emilia knew what would happen before it did. There was a change in the air, as if the pressure suddenly dropped, as if the air became brittle cold, as if the heart stopped beating. A high pitched whine rang out just before Percy and Annabeth struck the chains, like the sound of an incoming rocket.

An explosion rocked the hillside, a wave of heat knocking all of them backward. Dark shrapnel ripped through Krios and Hyperion, shredding them as easily as wood in a chipper.

STINKING PIT. A hollow voice rolled across the plains, shaking the warm fleshy ground.

Bob staggered to his feet, unscathed. He'd managed to shield Small Bob, who had now crawled into his coveralls. "Tartarus," said Emilia shakily, standing up. "Get in the– fuck."

Percy and Annabeth looked just like themselves, the Death Mist gone. "Go! Go now!" she shrieked, looking around wildly as the voice rang disdainfully, TITANS. LESSER BEINGS. IMPERFECT AND WEAK.

In front of the Doors of Death, the air darkened and solidified. The being who appeared was so massive, radiating such pure malevolence, that Emilia finally understood why people were scared of her presence. If she was even a fraction as terrifying as this being, it was no wonder that humanity as a whole tried to steer clear of her.

He had black iron boots, each as large as a coffin. His legs were covered in dark greaves; his flesh all thick purple muscle, like the ground. His armored skirt was made from thousands of blackened, twisted bones, woven together like chain links and clasped in place by a belt of interlocking monstrous arms.

On the surface of the warrior's breastplate, murky faces appeared and submerged— giants, Cyclopes, gorgons, and drakons— all pressing against the armor as if trying to get out. The warrior's arms were bare—muscular, purple, and glistening—his hands as large as crane scoops.

Worst of all was his head: a helmet of twisted rock and metal with no particular shape— just jagged spikes and pulsing patches of magma. His entire face was a whirlpool— an inward spiral of darkness, just like Nyx. As they watched, the last particles of Titan essence from Hyperion and Krios were vacuumed into the warrior's maw.

Percy's voice sounded small, "Tartarus."

The warrior made a sound like a mountain cracking in half: a roar or a laugh. This form is only a small manifestation of my power, said the god. But it is enough to deal with you. I do not interfere lightly, little demigod. It is beneath me to deal with gnats such as yourself.

"Uh..." Percy appeared ready to pass out. "Don't... you know... go to any trouble."

You have proven surprisingly resilient, said Tartarus. You have come too far. I can no longer stand by and watch your progress. Daughter of Eris, you'd be wise to cross the Acheron anew and seek refuge in Nyx's home. You'll be driven mad when you see what I will do to your friends.

Tartarus spread his arms. Throughout the valley, thousands of monsters wailed and roared, clashing their weapons and bellowing in triumph. The Doors of Death shuddered in their chains.

Be honored, little demigods, said the god of the pit. Even the Olympians were never worthy of my personal attention. But you will be destroyed by Tartarus himself!