[in perpetuum et unum diem]

[alternate universe]

The General leant against the wall of the Palace's torture chamber, arms folded across her chest. Shouts and screams and cries of agony filled her ears—a familiar sound to the dark-haired leader. She watched with narrowed sea-green eyes as Menoetius, a leader of a smaller troop in the Regiment, dragged the thin blade across the blond boy's bare chest.

Flynn Hale cried out in agony, his head dropping as he grit his teeth. His fists tightened around the chains that held him bound to the wall, and with heaving exhales, he looked back up and met the General's gaze full on.

"That all you've got?" He spat out blood, returning his gaze to the General's.

Tessa cocked her head to the side, a slightly bemused smile on her lips. "You've got some fire to you."

Flynn set his jaw, exhaling slowly out of his nose. "What do you want from me?"

The General shook her head to herself, pushing away from the wall. "I want to see you break."

"Little chance of that happening."

"Oh, really?" Tessa quirked an eyebrow, her eyes flickering with danger. She waved her hand slightly, and Menoetius raised his weapon.

Flynn didn't so much as flinch.

Tessa lowered her hand, eyeing the prisoner before her. "You're unaware of the purpose you serve, aren't you? Well, Flynn, let me shed some light on your situation. You were taken from your universe as a way to lure your friends here. They'll be destroyed, the Regiment will rule in all universes, and then we all go home happy. If you don't cooperate, if you so much as try to pull anything, I'll make sure you pay for it."

"Aren't I already paying for it?" The prisoner groused, breathing heavily.

Tessa's lips stretched into a thin line. "What was the name of that little girlfriend of yours? Amelie?"

Flynn's face paled, and Tessa knew she'd struck a nerve. Blotches of anger formed on his fair complexion. "Don't touch her. If you so much as lay a finger on her, I swear to the gods—"

"There are no gods to swear to here," The General interjected, venom like barbs in her words. "Now, let me finish. If you refuse to cooperate, I will make sure that your little beloved sorceress suffers a fate worse than any death. Understand?"

Flynn struggled against his chains, so hard that for a split second, Tessa was worried they would come lose. There was an animalistic fury in the boy's blue eyes, backed by a sense of fear so vivid, that Tessa could almost feel it.

"Don't hurt her. Hurt me, torture me, kill me; I don't care. But don't lay a hand on her, I'm begging you." The prisoner pleaded.

Tessa clasped her hands together, a sly smile on her face. "Then I believe my work here is done."

And with that, she turned on her heel, stalking from the room. The doors swung shut behind her to the sound of Flynn's screams as his torture continued, and Tessa had barely made it a few feet from the chamber's threshold when the pang hit.

Images of a crumbling pavilion filled with demigods donning armor of all kinds ran through her head. She saw a wall of magic bursting into smithereens, as a boy who must have been Flynn was plunged through it. And then there was Tessa of the other universe, screaming at the top of her lungs.

And just like that, the vision was over.

The General caught her breath, eyeing either direction of the hallway to see who had seen. Thankfully, no one was around. However, that didn't stop her. She marched down the hallway, her heart still pounding.

~~

"What do you mean that the leader of the Valiance has disappeared?" The General's voice radiated through her council's chamber, where two of the four other members of her Elite were seated.

Reese Hale reclined lazily in his seat, watching his commander with bored sapphire eyes. "I mean that I've searched everywhere, and the kid is gone. Some witnesses report a portal being opened, but the reports aren't credible."

The General's eyes widened, and she whirled back around. "So it is possible that our enemy of our own universe has gone over to our enemy from the alternate universe?"

"Relax, Tessa," Kaden chimed, his voice ever soothing. Her second tapped his fingers against the onyx tabletop, eyeing her carefully. "We'll find him."

The General shook her head, beginning to pace. "Where's Dale?"

"Overseeing her position. You were the one to make her the new ruler of the Underworld, remember?" Reese drawled.

The General met her Third's gaze, fighting the urge to have him reprimanded for his tone. However, she sighed. "Get her. Issue a mission for her to start implementing her own abilities into the operation."

"On it." The blond boy pushed himself from the chair he was in and left the room, leaving Tessa and Kaden alone.

Tessa stalked over to a wall filled with reports and images of the insurgent group, Valiance, which featured Matthew Baines' face just about everywhere. He knew too much about how the Regiment and their operation worked. If that got out to the other side...

"You're fuming, Tessa," Kaden called. Tessa didn't need to turn around to know that he was approaching her, doing his best to soothe her nerves.

"An understatement for what I'm actually feeling, but nice try," The dark-haired girl snapped. She turned from her position, finding Kaden behind her.

"He won't get far," Kaden said in a soft voice. "We'll find him, torture him for his crimes, and then kill him together. It'll be fun."

"Kaden," Tessa stressed her lover's name. "He knows."

Her Second's emerald eyes widened slightly in realization, but he wrapped his arms around Tessa as if the news didn't matter. "What do you want me to do?"

Tessa sighed, racking her brain for a strategy. "Arrange for Maxwell to head back to the alternate universe and stop Baines' next move."

"But if Baines finishes the job, we can just find him and kill him, can't we? No harm done. If anything, he'd be helping us out." Kaden figured.

Tessa met his gaze. "He's probably allied himself with our friends on the other side. We can't risk the possibility of them figuring out how to...sever the bond. Do you understand?"

With a sigh, her lover nodded. "I'll issue the command later."

Tessa knit her eyebrows together. "Why not now?"

Kaden's eyes darkened, and Tessa's heart skipped a beat as her lover smirked. His hands approached the zipper at the front of her jumpsuit and tugged it down. "Because I still have to give you your birthday present, remember?"

~~

[original universe]

Tessa's eighteenth birthday had begun with a calm start, which she was all too grateful for. Given the events of San Francisco two days prior, Tessa still needed time to feel like herself again. A situation like that didn't just release its clutches on you as soon as it was over. Trauma took time to heal from, especially if it was bound to strike again.

Her fountain helped a lot. As soon as Tessa woke up and responded to the seemingly endless string of birthday texts, she grabbed a cup of coffee from the café and headed to the Garden of Minerva to enjoy the fall morning in peace. She sat on the edge of the large stone basin, listening to the babble of the water cascading from tier to tier and feeling the energy of the water surging through her veins.

And now? Well, Tessa was trying to figure out a pleasant way to end the conversation that had begun.

"Oh, sweetie, I'm just so proud of you!" Sera Brennan exclaimed from Tessa's phone. The daughter of Poseidon smiled, rolling her eyes with a laugh.

"Mom, it's just my eighteenth birthday." Tessa laughed. "I'm not winning the Nobel prize.

"But still," Her mother sighed. "You've been through so much, and I'm so happy that you've made it this far."

Tessa's heart panged at the double meaning in her mother's words. Sure, Tessa had done some pretty awesome things in her lifetime, but overall, her mom was more than thrilled that Tessa had survived it all to adulthood. She'd accomplished something that too many demigods hadn't been able to.

"Trust me, so am I," Tessa recovered from her momentary lapse and continued speaking. "But mom, I've really gotta go. This call is draining my phone's battery."

"Oh, sorry! I love you, Tessa. Have a great day today!" Sera beamed through the phone.

"I love you too, mom." Tessa spoke, sincerity in her voice. "I'll call you later."

And with that, Tessa ended the call, stuffing her phone back into her pocket. She took a breath, glancing at the water behind her. She loved her mother to death, but boy, did the woman know how to talk.

Tessa shut her eyes, basking in the slight chill of the September air. If her day could continue like this for only a little while longer, she'd be content. While she did love parties, she wasn't sure if she could handle one right at that moment. Maybe later on, but then again, she was apprehensive to see what Kaden had planned for the day.

Her birthday had always been an interesting thing to celebrate back at Camp Half-Blood. Tessa would wake up to Dale and Mark parked on either side of her bed, with a box of cupcakes and party hats at the ready. The day would continue with an exemption from her activities, even if her schedule was enjoyable. Reese and Kaden would sit with her, Dale, and Mark at meals, and after dinner, they'd all hang out and talk by the beach until the harpies made them go back to their cabins for curfew.

Tessa smiled at the memory, but felt her heart twist at the thought of Mark. She'd texted him just about every day since she'd gotten to college, but she could tell that something was up. His responses became shorter, less witty, and Tessa instantly knew that something would be wrong. And today, of all days, he hadn't even sent her a message.

With a sigh, Tessa pulled her phone out again. She tapped Mark's contact image and listened to the rings as the call ensued.

But there was no answer. And maybe it was Tessa's imagination, but the wind seemed to be a bit colder after that.

~~

"Can I open my eyes yet?" Tessa whined, a laugh laced in her voice as Kaden led her down the cobblestoned streets of New Rome.

"Not yet," Kaden sang. "We're almost there!"

Tessa heaved a dramatic sigh, but excitement began to stir within her. Kaden had told her to dress nice, but not too nice, and to trust him on this. She obeyed, but thanks to Pandora way back in the day, she was getting a little too curious.

"Alright," Kaden said at last, slowing to a stop. He came around behind her, letting go of her hands and gripping her waist gently. "Open."

Tessa's eyes fluttered open and she lit up like the celebration before her. He'd led her to the arena of New Rome, designed like the Colosseum, which had been decorated with streamers and balloons. Just about everyone that Tessa had ever met in the confines of the valley was within the arena, dancing and chatting as music—DJed by Jett—blared through the air.

"This is all for me?" Tessa asked incredulously, turning back on her heel to face Kaden. Her boyfriend was beaming, scanning her reaction.

"Do you like it?" Kaden asked, excitement in his voice. He was like a little puppy, just trying to make someone happy.

Tessa grinned, cupping his face in her hands and kissing him sweetly. "I love it."

Kaden pulled away from the kiss with a grin on his face. "Then let's head in." He laced his hand in hers, and together, they embarked into the arena.

Everywhere Tessa turned, people were there to wish her a happy birthday. They pointed to a table that had been set up in the corner, gifts stacked atop it. Then, under the spell of the music, they'd continue on in their festivities.

Kaden led her through the crowd to a secluded part of the arena, where their friends all sat. Upon seeing Kaden and Tessa's arrival, they sprang up and blitzed them, following suit with the wishes and the gifts.

"Nice party, Gray," Imogen folded her arms over her pink party dress, eyeing the Colosseum-replica around them. "I give it a 7."

Kaden looked mildly taken aback. "A 7?"

Imogen flicked her jade eyes to meet Kaden's emerald ones. "Continue to complain and I'll dock a point."

Kaden clamped his lips shut, even though Tessa could see the calculating look in his eyes. She rolled her own, pecking his cheek to settle him down.

"Tessa!" Sophia called, hand-in-hand with Alexia Prinz, her girlfriend. The two were beaming, and Tessa couldn't help but feel happiness for them—they'd endured a struggle of their own earlier that year, but thankfully, they were prospering.

"Hey, Soph," Tessa pulled the daughter of Athena into a hug. "How do you like the party?"

"Oh, it's great!" She nodded. "Little loud, but when in Rome."

"Did you just make a pun about Rome when we're in New Rome?" Tessa looked at the red-headed girl dubiously.

"You have no idea how much she does it," Alexia chimed with a laugh.

"I admire your strength to get through that," Tessa chuckled, nodding to the daughter of Pluto as she slung an arm around her girlfriend.

The two girls disappeared into the crowd of party-goers, and Tessa felt an arm sling around shoulders. She turned and saw Reese, bopping his head to the beat of the music.

"So you're an adult now? Welcome to the club," The son of Apollo winked.

"Gee, thanks." Tessa nudged the boy at her side. "It's such an honor."

"I know, it's quite fascinating," Reese continued. "But before I forget, here's your present." The blond boy handed her a large blue gift bag, filled to the brim with tissue paper.

Tessa rifled through the bag and upon finding the gift, resisted the urge to whack the son of Apollo upside the head. He'd gotten her slippers, but shaped like hammerhead sharks, bulging side-eyes and all...which was also the third year in a row that Reese had gotten her something shark-related.

"I decided to keep my streak alive," Reese grabbed one of the slippers, whacking Tessa with it lightly.

Tessa met his gaze, and using the other slipper, hit him back. They engaged in a small duel for a while, until Kaden came over with two glasses of something sparkly, confusion etched onto his face.

"Okay, so I'm gonna go," Kaden turned on his heel.

Reese reached out and stopped his best friend, turning him back around. "Not so fast, Praetor Pants."

"Is that the best you can come up with?" Tessa wrinkled her nose.

"Mark's not here, I'm kind of at a loss here, guys. Take it easy on me." Reese threw his hands up in exasperation.

Kaden rolled his emerald eyes. "Imogen's looking for you, by the way." He nodded towards the snack table, and with that, Reese departed.

Tessa stuffed her shark slippers back into the bag, setting it down on the gift table nearby. She returned to Kaden, who handed her one of the glasses he was holding. "What's in this?"

"Diluted nectar," The son of Venus responded, holding his own glass up. With a grin on his face, he grabbed Tessa's free hand and led her towards the stage where Jett was set up, arranging the playlists for the night. As soon as the people of the legion saw their praetor, they stopped, the music fading out.

"I'd like to thank you all for coming tonight," Kaden spoke, his voice echoing across the arena. "It's a very special day, which deserves to have light shed upon it for the blessing we received on this day eighteen years ago. Today marks the eighteenth anniversary of the birth of one of the world's heroes, of one of the saviors of Rome. Today marks the day when every monster, spirit, and demon would have to reevaluate their own strength compared to that of the girl who was born. Today marks the day that the love of my life was brought into the world."

The audience 'awwed' at that, and Tessa felt a blush burn onto her cheeks, but Kaden kept going.

"While Tessa is a Greek, she's done more for Rome and Camp Jupiter than you all could ever imagine. She saved us all, and will continue to save us, no matter where she is. I'll follow her into any decision she makes, and I hope you all see the bright light that this girl has within her, because she truly is inspiring. And so, I'd like to make a toast to my love, my sunshine, my world: ave, Thalassa Arielle Brennan!" Kaden raised his glass, looking at Tessa with a bright look in his eyes.

The crowd cheered after echoing the hail, and roared even louder when Kaden pulled Tessa in for a kiss. And even if the world was watching in that moment, Tessa didn't care, because right then and there, it was just the two of them.

Kaden pulled away with a smile, and nodded to the crowd. "Enjoy the night!"

With a wave of his hand, a storm of shimmering confetti fell onto the crowd of party-goers with grace. The legion cheered as the music blared back again, and Tessa took a moment to admire the scene: a horizon of light and laughter, all for her.

~~

The party was going great, and Tessa danced her way off the dancefloor for refreshments. Everywhere she looked, she saw her friends having the time of their lives. Madi and Ben danced together in the center of the pulpit, smiling and laughing. Kaya allowed Imogen to pull her into the dance circle that she, Reese, Kaden, Sophia, Alexia, and Mallory had formed. Julius, Eli, and Charlie were challenging one another to see how many Cheez-Its they could eat in one bite, and Luci—the poor girl—played moderator nearby.

Tessa surveyed it all, a smile on her face as she raised a glass of water to her lips. Even with all of the darkness encroaching upon them, there wasn't one ounce of light that couldn't pierce through it. Even shadows could wait.

"Lovely party," A deep voice shook Tessa out of her reverie. "I'm sure Dionysus would approve."

Tessa choked on her water momentarily, looking beside her with wide eyes. "Father?"

Poseidon stood at her side, a smile on her face. The god of the sea was donning mortal clothing rather than his Olympian robes—shorts and a Hawaiian shirt that made Tessa cringe. Tessa wondered if the Romans minded her father's presence, given their slight tensions towards his Roman form.

"Happy birthday, Thalassa," Poseidon nodded. "I'm proud to see you come so far."

Tessa felt her throat go dry. She'd only spoken to her father once in her life, and those had been under much more dire circumstances. She wondered if like last time, he had any omens to present her with, or if he'd merely wanted to attend his daughter's birthday.

"Thank you," Tessa managed, exhaling slightly. "It's good to see you."

A sad smile stretched across her father's lips, crinkling the smile lines around his turquoise eyes. "I apologize for not maintaining contact with you, my dear. Zeus has his policies, and today was the only day that I could manage to see you."

Tessa nodded. "No, it's okay. I understand. You're a god, you've got more important things to deal with."

Poseidon eyed Tessa carefully, as if surveying her on a level that she couldn't determine. "I'm sure you've been occupied as well."

Tessa looked at her feet before returning her gaze to her father's. "I can handle it. I won't disappoint you, father."

The god of the sea smiled. "I know, Tessa. Believe me, I do. You, Madi, Lukas...you all have made me a very proud father and it pains me that I can't be there for you all more. But while I am here, allow me to offer some advice.

"I know you're frightened about what is to come, Tessa, but you must maintain a grip on who you are. The alternate universe has a way of seeping into this one, and it'll infect your mind with its ideals. You cannot let that happen, to yourself or to your friends. As long as you know who you are, and accept what you are capable of, you'll be able to overcome it all." Poseidon rested a hand on her shoulder.

Tessa searched her father's eyes. "I understand. Thank you, father."

"Don't mention it," Poseidon shrugged, stepping back as if he'd told her something mundane rather than a message as crucial as this. "Now, if you'll excuse me, I'd like to have a word with that boyfriend of yours."

Tessa stifled a laugh at the thought of Kaden meeting her dad, but nodded. "He's over by the stage."

Her father smiled to her in thanks and shuffled his way through the crowd, and in that moment, Tessa could pretend that she was a normal teenager turning eighteen, with her friends having the time of their lives and her dad having a chat with her boyfriend. It was almost vivid enough to fool her.

Almost.

~~

Around midnight, the party ended. One minute, Tessa was dancing around to music with Kaden and her friends, and the next, she was walking home. Kaden was at her side, his hand laced in hers, and the substitution of crickets for blaring pop music was somewhat of a relief.

"Did you have fun?" Kaden swung their linked hands as they walked down the silent cobblestone streets of New Rome.

Tessa nodded. "Thank you," She smiled up at the son of Venus.

Kaden grinned, pressing a kiss to her temple as they continued on their way. After a while, they reached a large Roman villa on the outskirts of the city, near the Principia. The marble walls gleamed in the starlight, a fountain babbling in the front yard.

Tessa blinked through her stupor. "Where are we?"

Kaden looked at her with a blank expression. "This is my villa."

Tessa made a face. "But...your dorm is in the Principia, right?"

Her boyfriend pulled a sigh, but laughed through it. "Tess, I don't live at the Principia. That's just where I work. Sure, they have spare bedrooms for the praetors to use during late nights of work, but we're given our own villas."

"And you're just now telling me this?" Tessa matched his look.

"Your dorm's closer to the action; sue me." Kaden shrugged, but smiled through it. "Come on in, you must be exhausted."

Kaden led Tessa through the front gate and to the door. They stepped into his villa, and instantly, Tessa felt like she'd entered some weird cross between ancient history and the modern world. A large marble staircase stood before them, compete with a runner along the steps and golden railings leading to the second floor. The floors glittered in the low light, and as Kaden led her upstairs, Tessa spotted a living room filled with leather sofas, glass tables, and the biggest flat-screen TV she'd seen in her life. Replicas of Roman weaponry hung along the walls, as well as tapestries and banners and maps and just about anything else a militia officer would possess.

The next thing Tessa knew, she was standing in Kaden's bedroom. It was massive, that was a given. The floors were a mahogany hardwood, matching the red walls and the four-post plush bed along the wall. A large closet and personal bathroom flanked either wall, as well as a desk and another flat-screen TV on the wall across from the bed.

"I'm sorry, this is your room?" Tessa motioned around the room, kicking off her shoes.

"Yep."

"So how do I become praetor?"

Kaden tossed his head back and laughed. "This isn't even the best part. Come on, you'll love this." He grabbed her hand and led her to a pair of French doors on the opposite wall. He swung them open, and led Tessa onto a wide marble balcony.

But as soon as Tessa stepped out into the night air, she gasped as she looked up.

The night sky stretched on like a glistening stretch of midnight fabric, dotted with the brightest stars that Tessa had ever seen in her life. A full moon hung like a pendant in the sky, illuminating all that it touched. Constellations were laid out above her as vividly as she'd known. She didn't have to search and guess which one was which; she could see them all above her. It was the most beautiful thing that she'd ever seen.

"Kaden..." Tessa breathed, her hands on the golden railing.

"I knew you'd love it," Kaden chimed, his voice slightly breathy with relief.

"It's stunning," Tessa whirled back around to face her boyfriend, watching her the way she was watching the sky.

Kaden smiled, meeting her halfway across the balcony. "Now you know how I feel whenever I see you."

Tessa tried to fight the blush on her cheeks, but to no avail. That was her curse for dating the son of the goddess of love—he always managed to make her blush and give her butterflies. But maybe it was more of a blessing.

"I've wanted to show you this for a while, but I wanted to save it for a special day. It'd have more of an effect. Besides, I know how much you love stargazing, and if I can't bring you the moon and the stars, I can at least give you a way to see them close up." Kaden snaked his arms around her waist.

Tessa smiled, lacing her arms around Kaden's neck. "Thank you."

Kaden grinned, pecking her lips. "I love you so much, Tessa. I know I tell you this a lot, but with each day, each hour, I find a way to love you even more. You're intelligent, beautiful, powerful, yet sincere, fragile, and sentimental. When I said you have a light inside you, I wasn't kidding. There's something that burns bright about you that I can't put my finger on, but I can't get enough of it. You're all I want, Tessa, and I will fight as hard as it takes for us to have our own happy ending when all of this is over. I promise on the River Styx."

Tessa searched Kaden's eyes, and found nothing but an everlasting love within them, reserved for her. In that moment, she wasn't sure about the war about to come, about the universe on the other side, about the danger around the corner. No, as she and Kaden stood beneath a sky full of stars, she was only entirely aware of the eternal love she felt for him, as prominent as the beating of her own heart. If there was one thing that was certain about the future, it was her and Kaden. Not even the Fates could break a bond so strong.

"I love you," Tessa breathed, and closed the distance between them. She pressed her lips to his passionately, and when he kissed back on instinct, she sighed in content. They were two pieces of a puzzle, destined to be together.

Tessa's hands slipped into Kaden's hair as Kaden's began to run up and down her figure. Tessa suppressed a shiver at the feeling, but soon enough, she was blindsided by love and only love.

Kaden picked her up bridal style, their lips still connected. He carried her back into his bedroom, setting her down on the blush covers of his bed and hovering above her. They kissed one another with all of the love in their hearts, their hands roaming one another's figures.

Tessa's heart skipped a beat as Kaden pulled away, just a centimeter, his eyes searching hers. "Are you sure about this?" he whispered.

Let the gods bless his soul, Tessa thought.

"I've never been more sure," Tessa whispered back, pressing her lips to his once more, her eyes fluttering shut.

With that, Kaden tapped the zipper of her dress, as if asking if it were alright to unzip it. And as soon as Tessa gave the okay, he made sure to act quickly, yet gently.

Clothes were shed with grace, and with the rapid beats of their hearts and the brushes of their lips across one another's, Tessa and Kaden allowed themselves and their love to shine through like the full moon in the sky above, their affection as everlasting and impermeable as the illuminated night sky.