[in inceptum finis est]

Tessa's heart punctuated her footsteps as she ran down the paths of campus. Imogen and Dale tore down the trails behind her, their rapid footsteps echoing her own. As Tessa ran, she couldn't process what she was about to do or see, but all she could think was how much wrath and fury she was harboring. The monster within her was purring, as if it would finally have a chance to take over.

"Tessa, for the last time, what's wrong?" Imogen called from behind Tessa, weaving around a corner.

Shaking her head, Tessa continued running. The Principia was dead ahead, and hopefully, no one was dead yet. Given the darkness of the dimming sky and the immaculate columns of the praetorian building, the Principia almost resembled a tomb.

"You'll see," Tessa breathed, tearing up the front steps of the building.

Kaden's office was on the second floor of the Principia, so Tessa didn't waste a second as she sped across the glittering marble floors. She leapt past the tribute to Alex Devan--the son of Mars who passed away in the Battle of New Rome that January—and booked it up the stairs. Dale and Imogen continued on behind her, and with each footstep, Tessa's heartbeat intensified.

Finally, she reached Kaden's office, and felt a small twinge of panic when her gaze fell upon the opened door. No sound of a struggle crept out into the hallway, but then again, Tessa wasn't sure if that was a good thing or a bad thing.

Tessa took a deep breath, digging Tempest out of her pocket. With a tap of its bejeweled end, the bronze hairpin elongated into a three-foot Celestial Bronze sword. She swung it around in practice before stepping into the room.

"Kaden?" Tessa called, her voice reverberating across the vast room. Like the rest of the Principia, Kaden's praetorian office was decked out in white and red, violet and gold. Maps of the camp and the world hung along the walls, as well as artifacts of Ancient Roman weapons. A mahogany desk sat in the center of the room, with papers and files strewn across the top.

A blur of movement caught Tessa's eyes, and the next thing she knew, Tempest's tip was at Kaden's throat. Her boyfriend looked at her sheepishly, despite the grave look in his emerald eyes.

"We need to stop meeting like this, Tess," The son of Venus quirked an eyebrow up, a smile on his lips as he held his hands up in mock surrender.

Tessa felt her cheeks burn. "Sorry," She mumbled, lowering her sword. "But where is he?"

At that moment, another figure emerged from the shadows—Reese. Kaden must have called him over for back-up. "Kaden'll lead the way."

Kaden's amiable visage crumbled like Rome's destruction, revealing the truth beneath. "This way."

He turned on his heel and walked towards a side room connected to his office. Tessa glanced behind her at Dale and Imogen—who had armed themselves—before following Kaden.

"How did he get in?" Tessa asked, catching up with her boyfriend.

Kaden shook his head. "I have no idea, but whoever let him through, I'm going to pulverize them."

The son of Venus rested a hand on the golden doorknob of the side room, giving Tessa warning glance before pushing it open. And there, unconscious and bound, was Matthew Baines, son of Ares.

Instantly, the fury that Tessa had suppressed in the past year towards the traitor flared within her. One look at that stupid face, and Tessa fought the urge to skewer him with Tempest once and for all. It had been over a year since the son of Ares had sold them out to Deimos and his band of enemies, causing a minor battle at camp and practically sending Tessa, Kaden, Reese, Dale, and Mark on a suicide mission. Matthew had faced trial on Olympus, and was sentenced to twenty years in the Fields of Punishment. But how he escaped was a mystery to Tessa.

"Who's that?" Imogen crowed, her jade eyes narrowing in the dim light of the office. "He's sort of cute."

Reese gave his girlfriend a funny look. "Excuse me?"

Imogen waved her hand in dismissal.

"He's a traitor," Dale interjected, flashing a deadly look at the daughter of Cupid.

Imogen frowned, a darker look on her face. Tessa knew what she must have been thinking of: Vinny, her former co-centurion.

"Then why's he here?" The blonde girl asked. "Reese told me about this kid. Wasn't he sentenced to the Underworld?"

"He was," Kaden confirmed, his jaw set and toned arms folded across his chest. "So the question is how did he get out?"

The five demigods watched the unconscious son of Ares, and all five jumped when he began to come to. Matthew's eyes fluttered open, wincing shut once before wrenching open again. He tugged against his bound hands and feet, but before he could so much as attempt to remove them, Tessa struck.

"One more move and you're a dead man," Tessa snarled, Tempest's blade against the boy's neck.

Matthew eyed Tessa carefully, and began to smile. "Even here, you're terrifying."

Tessa faltered for a second. "What do you mean by that?"

Matthew gave Tessa a funny look. "Aren't you Tessa Brennan? Daughter of Poseidon?"

A chill ran down Tessa's spine, and she lowered her sword. "I am."

"What are you doing here, Matthew? How'd you escape the Underworld?" Kaden drew his own sword, fury blazing in his emerald irises.

The son of Ares held up his bound hands, as if to surrender. "Firstly, I've never been to the Underworld. Secondly, I'll explain if you untie me."

Tessa barked in laughter. "And why the hell would we do that?"

Matthew met her furious gaze. "Because you've got the wrong guy."

"Then I suggest you explain yourself because the only way you're getting out of those bonds is if you start talking," Imogen snapped, her silky voice laced with charmspeak.

The son of Ares huffed a breath, but settled against the wall he was leant against. "My name is Matthew Baines, and I need your help to take down the Regiment."

"The Regiment's been destroyed," Kaden interjected.

Matthew shook his head. "Not where I come from. There, the Regiment rules the world of mythology, and those who oppose it...well, I'm one of the lucky ones."

Dale blinked a few times, shaking her head as if to clear her head from a trance. "What do you mean by that?"

Suddenly, the realization dawned on Tessa like a new horizon. She found herself back in New Orleans, atop the pavilion of portals as Orion explained to her their purposes. The portals could lead anywhere from different locations to alternate timelines, before they were destroyed.

But they weren't. Amelie had ruled them functioning, but unstable.

"He's not from our universe," Tessa muttered in astonishment, looking up at her friends in horror. She turned back to Matthew, who held an impish look in his eyes. "Aren't you?"

The son of Ares smiled. "That is correct."

Tessa felt the wave of panic begin to surge within her, like a storm forming at sea. "But how is that...what?"

"Allow me to explain," Matthew cleared his throat. "In my universe, being a demigod is even scarier than I imagine it is here. The Regiment recruits those of both mortal descent and immortal, in order to carry out all sorts of horrors. As of late, the General has one plan and that's to take down Olympus in all dimensions. The Olympians are condemned to Tartarus in my world, and now, she's coming for yours.

"I was a part of an insurgent group called Valiance back in my universe. Unfortunately, on one of my operatives, I was captured by the Regiment. I was about to face execution, led by the General herself, when a friend of mine—another prisoner—was able to create a portal. When the time was right, I leapt through it and it brought me here.

"I don't know what the Matthew Baines of this world did to earn him a place in the Underworld, but I can guarantee you that he's better off there. If the General and her Regiment make their way to this world...well, there are worse fates than death." Matthew spoke, and his words took effect instantly.

A chill spread across the room, and Tessa felt numb all over. It wasn't over, then. She wasn't in the clear. The portals still worked, and whoever this General was, she was hellbent on taking over all dimensions where the Olympians were still in power.

"Wait a second," Imogen said, a realization dawning on her face. "If there's another universe filled with people who look like us...

Reese's eyes widened, meeting Imogen's gaze. "Then the people we've been seeing haven't just been look-a-likes, have they? They were ourselves from this alternate universe."

Matthew's eyes bugged out at that. "You've seen your doppelgangers? Oh, that's not good."

Tessa took a deep breath, trying to quell her rising anxiety. "Why not?"

Matthew shook his head. "In my world, you three," He jerked his chin at Kaden, Reese, and Dale, "are apart of the General's Elite. So if you've been seeing them here, it only means that their plan is close to initiation."

Imogen knit her eyebrows together. "If Kaden, Reese, and Dale are a part of the Elite, then who's the General?"

As soon as Matthew met Tessa's gaze, nerves settled in her stomach like a weight sinking to the bottom of the sea. "She is."

Tessa shook her head. "That can't be true. I'd never—"

"You might not be evil here, but back there, you're what people fear. The daughter of Poseidon who renounced her own father and banished him to Tartarus. The leader of the Regiment who presides over every mission, every capture, each torture session, interrogation, and execution. All while sitting atop her throne in her jumpsuit and golden belt."

A memory came to the forefront of Tessa's mind from earlier that summer. They'd been in the Twenties, and Tessa had seen a girl who looked exactly like her that wore a golden belt. She'd dismissed the encounter as a daze from alcohol and time, but now that Matthew confirmed the existence of this alternate universe, Tessa knew that the girl in the party had been her.

"I know it's a lot to take in," Matthew spoke again, his voice soft. "But you all need to accept it. That's the only way we stand a chance against defeating the Regiment: accept your darkness."

And just like that, Tessa felt like she'd been slapped. "What did you just say?"

Matthew knit his eyebrows together. "Accept your darkness?"

A labored breath escaped Tessa's lips in panic, images of the girl in her dreams that had to have been the General saying the same words. This was it, this was the prophecy coming to pass. Tessa's breaths became more frequent, and if she didn't get a grip, she'd slip into an attack.

"Guys, there's something I need to tell you," Tessa met the concerned gazes of her friends. "I've been keeping something from you all since this summer. I didn't think it was something to worry about, but given all of this, you need to know."

And so Tessa let it all come down, all of the secrets about the Prophecy that Vinny had taken her to see in Delphi. She repeated the prophecy of the Oracle, and as the final verse was spoken, she wished she hadn't seen the faces of her friends.

"It's all connected," Tessa concluded, nerves shaking her body. "It has to be."

Reese dragged his hands through his blond hair, a panicked look in his blue eyes. "If our evil doppelgangers are out to get us...then that wasn't Flynn we saw in London...wasn't it? It was his look-alike."

"Did you say Flynn?" Matthew spoke, averting everyone's gaze to his bound figure.

"Yes," Reese spat, his voice laced with venom. "Why?"

Matthew cracked a grin. "You really don't know?"

"No, but I suggest you tell me before I use you for target practice." Reese's blue eyes flickered with fury.

Matthew held up his bound hands as if to stop him. "It's just...the Flynn from your universe, you must think he's dead, right? He's not. He's alive. He was in the cell next to mine, we were friends."

Reese looked like he'd been hit between the eyes. "F-Flynn's...he's alive?" He whispered, tears welling in his eyes.

The son of Ares nodded. "At least, I hope he still is. It's been a while since I've seen him, but he should be alright."

Reese held his breath, and Tessa could relate to the influx of emotions the son of Apollo must have been feeling. Rejoice at knowing the fate of his brother, sorrow at what his fate included, and desperation as to how to get him back.

"If the Regiment and our look-a-likes are planning to come to this universe, how long do we have? What're their plans? Is there anything you can tell us?" Dale asked, a calculating look in her golden irises.

Matthew shrugged. "All I know is that the General has been sending her soldiers on individual missions to this world to sow fear into the minds of the mortals, so when Olympus falls, they can pass it off as a terror attack or something. Implementing tricks of the mist."

Tessa's eyes widened and she met Reese's gaze, and for a moment, his sapphire irises became the arctic blue ones of Eli Alistairs. The son of Ahklys' look-a-like had been the culprit of a fire in Las Vegas, and given Matthew's news, it only meant one thing: The Regiment was coming.

"How can we be ready?" Kaden took a deep breath, and Tessa could see that he was trying to remain calm. Here was one of his most hated enemies from another world, telling them about the versions of themselves that could ultimately kill them.

"Mobilize for war, train, do everything that you can to be ready for battle," Matthew suggested. "And I like I said before, you've gotta accept your own darkness. If you don't, they'll use it against you."

And suddenly, it all became too much. Tessa had never once feared drowning, but right now, she felt as if she'd been stripped of her aquatic abilities and was plummeting to the bottom of the sea. She needed air, she needed peace, and she sure as hell wasn't about to deal with all of this right now.

Tessa mumbled a quick apology to her friends and took off out of Kaden's office. She could hear the protests of her friends behind her, but she didn't stop to listen. She booked it out of the Principia and through campus, and as she ran, taking deep inhales of the crisp autumn air, she wondered if this was her breaking point, where the monster within her would finally come out.

She wondered if the General on the other side had once feared her own potential, had once reached the breaking point where she'd do anything to see her own worries quelled, no matter the cost.

Despite the dimensional separation, maybe the two daughters of Poseidon and Sera Brennan weren't that different after all.

~~

Tessa could control every body of water on the face of the planet, but that didn't include her own tears. She sobbed until she couldn't sob anymore, her tears staining her pillow, the hem of her shirt, the countless tissues that she'd used. Her throat hurt from the screaming, and her soul hurt from what she was to endure.

This wasn't supposed to be happening. Tessa was supposed to be free of this hell, of the torture she'd had to live with since she was thirteen. Who cared if she was the daughter of Poseidon? She wasn't a war machine. She wasn't a pawn of the gods to be used at their whim.

Tessa narrowed her eyes at the thought, half a sob away from cursing her own father's name. Her heart pulsed in sync with the purr of the darkness within her, challenging her, daring her to end it all.

A knock at her door stopped Tessa from making that decision.

The daughter of Poseidon sniffled, getting out of her bed. She padded across to her door and swung it open, already guessing who it was. Her boyfriend filed in, shutting the door behind him and facing Tessa.

"Tessa," Kaden breathed at the sight of her, his emerald irises shattering with minor heartbreak. "Come here."

He spread his arms, and Tessa didn't miss a beat. She swept into his embrace like it was where she belonged, a shuddering sob racking her body as his arms wrapped around her.

"I'm so sorry, Tess," Kaden murmured, running a gentle hand up and down her back to calm her down.

Tessa's eyes welled up again, and she shut them tight. Maybe if she kept her eyes close for the whole time, she wouldn't be able to see how this new war would play out.

"I want to know why," Tessa croaked, pulling away from the embrace slightly. "Why do we have to keep enduring this?"

Kaden shook his head, reaching a hand up to brush away her tears. "I don't know, love, but we'll get through it. We always do. I still believe in us."

Tessa leant into his touch, a sigh escaping her lips. She couldn't think of anything to say, all she wanted to do was sob her heart out and damn the world. Tears continued to slip down her face, and just like that, Kaden picked her up bridal style and set her down gently on her bed. He cuddled in next to her, and kissed the top of her head.

"Will crying make you feel better?" He asked, searching her eyes. "Because if it will, I want you to cry until there's no more water within your eyes."

Tessa shook her head, huffing a breath. "I'm the daughter of Poseidon, I have an unlimited amount of water within me." She rested her head against Kaden's chest.

Kaden chuckled lightly, and the sound was enough to lift Tessa's spirits, if only a miniscule amount. "Then what will make you feel better?"

Tessa racked her brain. There were a lot of things that would make her feel better: food, seeing her friends, being with Kaden. However, only one thing shimmered through the other possibilities like a beacon of hope.

"Tell me about a future that we don't have to be afraid of," Tessa decided, turning on her side to face Kaden.

The son of Venus smiled, brushing a finger down her cheek. "Well, let's see...in this future, all of the wars and battles are behind us. We've served our time, we've fought our causes, and now we're free to live life to the fullest. We graduate from NRU in two years, alongside all of our friends. Flynn's back, and Mark's there too, and the whole gang will be back together again. We'll all have our degrees, and we'll be pursuing our passions."

"That sounds great," Tessa sighed.

Kaden's smile deepened. "Doesn't it?"

Tessa nodded, already beginning to feel her panic attack fading away. Having Kaden distract her like this, or anyone really, it did wonders to bring her out of the mausoleum of fear that was her mind and back to reality.

"You and I get an apartment back in New York, or maybe San Francisco. Whichever one you prefer, I'll be fine with. We'll spend our days looking for furniture, eating at all of the restaurants that our select city can offer, and having movie nights whenever we can. You'll be a successful journalist or publisher or author or marine biologist—maybe even all of the above because you're that good—and I'll be a doctor." Kaden's emerald eyes shimmered with a thoughtful gaze, like he could see that future right before them. He met her gaze happily. "And we'll live out our days in happiness and bliss, alongside each other and our friends, with no battles and wars to worry about."

Tessa found herself smiling, and she reached a hand up to cup Kaden's cheek. "I love you, Kaden." She whispered. "Thank you."

Kaden smiled, pressing a sweet kiss to her forehead. "I love you, too, Tessa. Always have, always will." He met her lips shortly, before pulling away, a hint of concern in his eyes. "Do you feel better?"

Tessa nodded, shutting her eyes and settling against Kaden. She listened to the sound of his heartbeat, and prayed to the gods that moments like this would last forever to outshine the darkness, outlast the pain.

~~

Sunlight streamed through the windows the next morning, and Tessa stretched in her bed. She blinked her sea-green eyes, sitting up to find the other side of her bed empty, save a note attached to the pillow.

Dear Tessa, I'm sorry I had to leave before you got up. I hope I was quiet, I didn't want to interrupt your rest. Anyways, I'll be sure to meet you after class today at the coffee shop—I won't send Reese again, don't worry. I hope you're feeling better, my love. Love, Kaden.

A sleepy smile laced Tessa's lips as she set the note down. She turned and glanced at her clock, sighing in relief when she realized that her first class wasn't for another two hours. All the more time to mentally prepare herself for what was to come.

However, the universe had other plans.

Tessa had barely gotten out of the covers when there was a frantic series of knocks at her door. The daughter of Poseidon arched an eyebrow and slowly made her way over to her door, swinging it open.

Madi stood outside, a wild look in her hazel eyes. Her dark hair was tied up, and while the second daughter of Poseidon looked like she hadn't slept in days, she seemed alert. However, it was the red on her half-sister's hands that caught Tessa's attention.

"We need to talk."

~~

[alternate universe]

The General sat like a panther atop her throne, crystalline eyes honed in on a point in the distance. She was a volcano awaiting to erupt, a storm about to break, but she did all that she could to hold her emotions back. Logic was to fuel her next move, not the anger she was harboring in her soul.

"So the leader of Valiance is reported to be on the other side?" She clarified, her voice echoing across the cavern, punctuated by the flicker of the torches along the obsidian walls.

The lieutenant knelt upon the dais nodded. "We thought he was dead, but he somehow accessed a portal. We aren't sure yet, m'lady, but we can be."

"Then see to it," The General snapped.

The lieutenant nodded. He turned to his side, waving off the two other soldiers under his own command, watching as they dashed away.

"Lieutenant, do you know what this means?" The General asked, standing from her throne.

"M'Lady?"

The General sauntered off the dais, towards the mirror along the wall. "It means that we risk exposure to the other side. So here is your mission, Lieutenant: go back to the other side—seeing as it is your own world—and carry out Operation Psi. See to it that our...friends are kept occupied while we mobilize."

Silence answered the General's response, and seeing as all commands were to be accepted, the daughter of the renounced sea god turned on her heel. "Do I need to repeat myself, lieutenant?"

The soldier shook his head, chuckling under his breath as he stood. "Not at all, General."

"Then why the silence?"

And so Vindex Maxwell stared back at her, a traitor from another world, with a malicious look in his sapphire eyes. "I'm just eager to get back to San Francisco."