Title: Love by the Books
Pairing: Nico/Percy/Annabeth

Warnings: polyamory, threesomes, language

Rating: R for the sexings
A/N: I blame Heather/callunavulgari entirely 3
Disclaimer: I am actually not Rick Riordan, soooooo.

Summary: Percy didn't intend to start including Nico in his and Annabeth's relationship, but it happens anyway (it's probably Aphrodite's fault).

Percy counted himself lucky that his girlfriend of five years was double majoring in archeology and classics, because any other girlfriend might have beaten his ass before the sentence was even out of his mouth. But rather than blowing him up, Annabeth started telling him stories from Greek and Roman mythology about gods and demigods having relationships with men and women – mortal and immortal – at the same time. When that wasn't enough, she pulled out her textbook full of historical studies of sexuality. Percy wasn't really listening; he was trying to decide on a scale of one to incineration how badly Nico was going to kill him. Evisceration was looking to be a pretty solid possibility.

An explanation is probably in order.

0o0

Life after the war with Gaea was absurdly quiet, and probably the closest thing to normal as any demigod had experienced. Suddenly Percy had to worry about more than titans and monsters that wanted to nom on his flesh: SATs and college applications took over his life, and he was narrowly accepted into a school not far from NYU, Annabeth's chosen destination. While they were both busy trying to build normal, mortal lives, some weekends still acted like camp reunions, especially after the rebuilding was finished. Percy and Annabeth were still dating as they started their third year at their respective schools, which was about the time things became much more complex.

Percy started an internship at the local aquarium the same year, which was where his past came back to haunt – or really, in this case, to distract – him. He was standing on a platform over the colossal mock coral reef tank containing approximately one thousand creatures – from Moray eels to adolescent Hammerheads to stingrays and Blue Tangs – giving a talk about conservation of Loggerhead turtles and their habitats while a marine biologist fed said animal when he cast his gaze through the crowd and realized he recognized one of their faces. Percy barely caught himself before a curse escaped his mouth mid-talk, and coughed to cover his slip. Across the tank, the very familiar face of Nico di Angelo seemed to snort with amusement.

"What the hell are you doing here, man?" Percy asked him after the talk was over and he'd managed to extricate himself from the crowd to find the other demigod leaning up against an exhibit about piranhas. He wasn't annoyed by any stretch of the word, just completely taken off-guard by his sudden appearance. Nico had made good on his promise to leave the mortal world behind after Gaea's fall; he'd made his emotions perfectly clear to Percy before leaving, which left Percy feeling incredibly stupid and blind. Percy had barely choked out an apology before Nico was kissing Hazel on the cheek and disappearing back into the shadows. She was the only one who could get in touch with him at all it seemed, though by all accounts there had been no plans for him to return.

At seventeen, Percy had to admit that Nico looked like he was much more at ease with himself than he was when he'd left. He was taller, and Percy grudging acknowledged when he pulled away from the piranha display that Nico was probably about an inch taller than him now. Still on the thin side, Nico at least looked like was eating more than a few pomegranate seeds and grapes a day; his hair was a mop of loose black curls, with strands falling across dark eyes that didn't appear nearly as sunken as they had four years ago. The bomber jacket was gone, replaced with a sleek black leather jacket that Percy suspected was made of drakon hide, but he hadn't strayed far from his favorite uniform of black jeans, shirts, and boots.

The biggest change was probably the fact that the corners of Nico's mouth were turned up in amusement at Percy; he had to process that for a moment, because the last time he'd seen Nico smile – really smile, not the false one built for lies and masking heartbreak – was Hades' triumphant return to Olympus with his only living son at his side.

Seventeen looked good on him.

Nico shrugged in response to Percy's question. "I hadn't been topside in a while, so I figured why not?"

"How'd you know I was here?"

"Once she let me go long enough to breathe and ask, Hazel told me you were still in New York. After that . . . this place seemed fitting. I got a lucky break, I guess."

"I'm really not a pro-tank person," Percy admitted with a wry smile, "but some of these turtles have got the weirdest stories. It's good to see you again, though – really."

They talked for a few more minutes before Percy's supervisor came looking for him. Nico looked ready to bolt after the man chastised him for not getting to his next post, but Percy caught Nico's arm before he could disappear again.

"I go to lunch in an hour. Stick around, we'll catch up," Percy offered, forcing down the memory of the last time he'd grabbed Nico's arm to keep him from running away; three years ago that had earned him a broken nose and a very bruised ego.

Nico didn't flinch or make to punch him again though; he agreed to stick around, and that was how it began. He'd show up at Percy's job and wander, or watch him give presentations about marine life, and they'd go out for lunch during his break. Nico would show up with takeout at Percy's apartment, and they'd play video games while Percy procrastinated on his projects. They developed a friendly camaraderie that Percy desperately wished they'd been able to form when they were younger – but better late than never. Percy found he really liked to try and make Nico laugh; it was a rare, bright sound, and Percy decided he wanted to hear it even more.

Annabeth was pleasantly surprised when Percy told her about Nico's reappearance during one of their sleepovers, and mentioned that they should probably have him over at some point. Now knowing and understanding why Nico had behaved so hostilely to them years ago, Annabeth wanted to move past that and, if she could, befriend the son of Hades. Percy admired her immensely for that, because her pride was often a topic of discussion that had ended with him wondering if he had a concussion. He'd worried, when he first mentioned that he missed Nico – missed hanging out with him, missed his dark humor and sharp sarcasm – that Annabeth might take issue with that. She, however, was the one to bring up his recent melancholy. "You really do miss him, don't you?"

To which Percy had nodded, saying, "Never thought I'd say it, but yeah."

"I could tell," Annabeth hummed, not a trace of resentment or worry in her voice. "He's grown on you a bit, I think."

0o0

The next time he saw Nico, the younger demigod was bridged over him with his arms framing Percy's body with a manic gleam in his eyes. Percy was just waking up from a nap and was startled by the image of Nico over him, and immediately his heart started to beat a little bit louder.

"Come hunt a monster with me," Nico said, a grin on his face. "For old time's sake?"

"I thought you didn't go looking for trouble?"

Nico smirked. "I found you, didn't I?"

Of course, monster hunting was an offer Percy couldn't turn down.

It was an exhilarating fight and afterwards, giddy with triumph, Percy introduced Nico to shawarma and the view from the top of the Rockefeller building. They sat on the edge of the tower, their legs dangling over the side as the city came to life with the setting sun as they crowed over their victory and swapped stories of monsters defeated in the most epic ways.

Percy was laughing at Nico's sarcastic comment about Medusa and her offspring when he realized that Nico wasn't laughing at all; he was staring at Percy with this lost, conflicted expression that made Percy's stomach do a barrel roll. It was the same expression he'd worn three years ago as the words "I loved you, you asshole" tumbled from Nico's mouth; Percy would never forget that, brain full of seaweed or no. He turned toward his friend, ready to ask what was wrong, but the words never left his mouth because Nico closed the space between them and kissed him.

Percy's heart hammered somewhere in the vicinity of his throat, utterly shocked because Nico was actually kissing him, and he was so close Percy could almost smell the lingering darkness from shadow traveling on his skin. He couldn't even process what was happening between them because his brain had come to an absolute standstill, and all that was left was sensation: Nico's lips were chapped, like he bit and worried them out of habit, but the kiss itself soft and cautious. Before Percy could respond, Nico pulled away, fear in his eyes and panic in his trembling hands. "Shit. Shit, I'm sorry. I'll go-"

Percy grabbed the front of Nico's shirt and pulled him back closer to him, kissing him into silence. Where the first kiss had been pretty chaste, Percy teased his mouth open with his tongue and swallowed the small, helpless sound Nico made. A second later he must have realized that Percy wasn't rejecting him, because his hands curled around the back of Percy's neck and into his hair, holding him close as they kissed. Even when Percy broke the kiss, Nico pressed their foreheads together, eyes squeezed shut as he rubbed his nose against Percy's. "Dick move, Jackson."

"Don't complain," Percy muttered, kissing him again and ignoring the small part of his brain prodding him and asking What the flying fuck? All he needed to know was that Nico's mouth was so sinfully wonderful, and he never wanted to stop kissing him.

That was when the image of Annabeth, her arms crossed and expression set in a form that clearly stated You are going to die slowly and painfully, Seaweed Brain settled in his mind.

"I need to talk to Annabeth," he said the next time the kiss broke, and automatically Percy knew he'd said the wrong thing when Nico jerked away from him, breaking all contact.

"Why do you have to bring her into this?" he hissed, wiping his mouth on his arm like that would erase the taste of Percy for good.

"Because I love her," Percy protested. "She's a part of me, and if you want to do this we're kind of a package deal."

"Why don't you just tell me to scram and get it over with?" Nico spat. His expression morphed from one of rage to confusion once he processed what Percy had said, though. "What the fuck are you talking about, a 'package deal?'"

"I like you," Percy said calmly. "And . . . I think we could be more. But I love Annabeth too, but I won't leave her and even though I have feelings for you . . . I don't know what to do."

Nico glowered, clearly not liking that answer. "Look – just forget about it. It never happened. I'm getting out of here." With that he pushed himself up from his spot and disappeared into the shadows, leaving Percy feeling incredibly lost and sad that once again, he'd driven Nico away with his own stupidity.

0o0

Explaining what had happened to Annabeth was kind of nerve-wracking; he probably wouldn't have said anything at all, but she was always perceptive of his moods. When he finally told her, she seemed surprisingly only somewhat shocked.

"You really like him?" she asked, her voice neutral if a little curious.

Percy nodded. "I do."

"So ask him out," Annabeth said simply, as if it was a no-brainer. "Greeks didn't have issues with polyamory, so I don't see why it should be a problem for us."

"Poly what?"

"Polyamory," she repeated herself, always patient with his seaweed-stuffed brain. "When a person falls in love and maintains a relationship with several people – with their knowledge and consent."

"And you are okay with that?"

Annabeth shrugged. "It was pretty commonplace in Greek society, and a bit in Rome, for men to take on male lovers alongside their female ones. There was a system called pederasty where men would court younger men so they could be their mentors and lovers, and eventually they'd initiate them into manhood-"

"Wow, yeah, I'm so glad that's totally relevant to me and Nico," Percy muttered, vaguely overwhelmed by her open response. He was still wondering how badly Nico was going to kill him for suggesting what she was implying, and whether this was all going to work out in the end anyway.

Annabeth smacked him with one of her textbooks; it was a rather thick book about sexuality in ancient Greece and Rome. "He can be your boyfriend – unless he comes to his senses – and I'll still be your girlfriend, but if you start picking favorites we'll have a problem."

With Annabeth's consent, Percy decided to ask Nico what he thought of the arrangement; the only problem there was that the son of Hades had once again dropped off the face of the earth. He wasn't responding to Iris messages, and he didn't show up at the aquarium or at Percy's apartment for nearly two weeks, either. Hazel apparently wasn't having much luck, either. Percy grew more and more distressed by this as time wore on, because he'd gotten so used to Nico's company that he felt the sudden loss clearly and painfully. Annabeth cheered him up when they got together, but he couldn't help the odd, hollow feeling, like there should have been a certain other demigod with them too.

Nico didn't reappear until halfway through the third week since their kiss. Percy was playing God of War and sniggering through an obnoxious boss battle when the son of Hades slipped out from the shadows, quietly watching him rearrange Ares' face. He was still half in darkness, as if he expected to need to make a quick getaway by way of the shadows.

"Can I join you?" Nico asked a few minutes later, when Kratos tore Ares apart and was standing on a field of victory and blood.

"Only if you promise to answer your messages the next time you decide to disappear."

Nico winced, but sat down on the couch beside Percy regardless. "Sorry. I will – but I really don't want there to be a 'next time.'"

Percy paused his game and turned towards the younger man, folding his legs up on the couch. "I missed you, you know."

"Did you tell your girlfriend what happened?" Nico asked bitterly, clearing his throat.

"Yes. And she asked me why I didn't just ask you out and see where it takes us."

Nico sputtered, staring at Percy with a mixture of confusion and distrust. "Did she break up with you?"

"No, but she's a lot more open-minded than I realized. I love Annabeth, Nico. I've loved her for years. The only thing that could change in this is how I feel about you, and if you're willing, I think we could be more." In his head a mantra that sounded like Please don't leave, please don't kill me was repeated over and over again.

Nico didn't answer for a moment. "You want me to share you with her."

"She's willing to share me with you," Percy countered. "And that's pretty big for her."

Nico fell quiet again for a long while. "I'm not actually that desperate, you know," he muttered loftily, crossing his arms over his chest and glaring at Percy out of the corner of his eyes.

"Nico."

Percy watched as his body language changed from guarded and angry to uncertain, shifting in his seat agitatedly. "You're serious about this? You're not just fucking around with my feelings, right?"

"Do you want me to swear on the River Styx?"

Nico shook his head and nearly launched himself across the couch; Percy wrapped his arms around him, kissing Nico and reveling in the feeling of being whole once more.

0o0

It's strange at first, dating two completely different people at once. Percy had to learn how to communicate and yeah, he kind of has to make a schedule those first few weeks so neither Annabeth nor Nico feels like he's favoring one over the other. He hangs out with Nico some days and with Annabeth on others, until eventually they all start to be more comfortable with each other. It took some time and more than a few bridges constructed by Percy for Nico to be more comfortable around the girl he'd spent most of his adolescence viciously jealous of, and Annabeth's nervousness around him was assuaged when he produced a rare volume for her that proved essential for a stressful research paper; Percy would never forget the look of abject terror and surprise on Nico's face when Annabeth pulled him into a crushing hug that lifted him off the ground a good inch before setting him down pouring over the old text like it was a lifeline.

It wasn't long after that that Percy realized just how treacherous and evil they could be when they put their heads together. It was during winter break and Annabeth and Nico had both converged on Percy's apartment to stay for a few days; Percy was sent out to get hot chocolate, and when he returned he found his girlfriend and boyfriend huddled over a few pages of notes on his kitchen table.

"What's going on?" he asked, wary and suspicious of their very innocent expressions.

"We're comparing notes," Annabeth responded, mirth in her voice that wasn't very well hidden at all.

"On what?"

"Our seaweed-brained boyfriend," Nico quipped, smirking at him. He turned to Annabeth and asked, "Have you noticed he really likes it when you bite him kind of hard?"

"The bruises remind him that he's ours, that's one of his favorite things," Annabeth stage-whispered conspiratorially to Nico. "Have you guys fucked yet?"

"I'm right here, guys," Percy muttered, waving to catch their attention.

They ignored him. Nico shook his head. Annabeth leaned in and whispered something in his ear that Percy couldn't hear, but the devilish look on Nico's face really should have told him everything he needed to know: he was totally doomed.

0o0

On the nights where Annabeth holed herself up in the library, leaving Nico and Percy to their own devices, they learned the most they could about each other. Nico's aversion to physical contact apparently applied to almost everyone except his boyfriend, though he still seemed nervous and hesitant when it came to cuddling. Those insecurities fell away piece by piece with Percy's affectionate nature helping that along. Percy could spend an infinite amount of time kissing, slowly driving Nico crazy with his fingers tangled in thick black hair, slipping his tongue past Nico's lips and swallowing his moans until he relaxed and became putty in his hands. He liked when his boyfriend bit a patch of skin just above his collarbone and worried that spot until bruises appeared on his flesh. Percy discovered that Nico was weak to his kisses, and he liked looking right into Percy's eyes when the son of Poseidon sucked his boyfriend's cock. He liked when Nico got a little rough, even a bit aggressive, biting his lip sharply in the midst of a steamy kiss or pushing him up against a wall and rocking his hips against Percy's.

Percy couldn't read his boyfriend's mind, but the look on his face as he let Percy's softening dick fall from his mouth and he licked the come from the corner of his mouth was pure, unadulterated triumph. You're mine, now.

0o0

The nights that Nico is down in the Underworld doing something for his father belong to Annabeth; she traces the bruises and hickeys left by Nico with her lips and leaves a few of her own. She and Percy have had more time to become comfortable with each other, so Annabeth finds this new addition to their relationship interesting.

"I kind of like him," she says one night, as Percy curls up at her side and uses her breast as a pillow after five orgasms between the two of them. It was kind of a marathon night, she supposed, but while Percy's head was usually filled with seaweed when it came to pleasing her he was incredibly dedicated. His skin is tacky with drying sweat, but neither of them cares enough to roll out of bed and shower. "Nico's a funny guy."

Percy shifted against her, slipping his arm across her stomach. "You just like plotting my doom with him. Admit it."

"You're very special to him."

Percy's mouth turns into a stupid kind of smile, an outward representation of the giddy feeling he got hearing those words. "I like him too. We should keep him."

"Good. He'll be my partner in crime."

0o0

The first time Percy and Nico have sex, it seemed destined to be a very awkward affair. It was just after Nico's birthday and Annabeth had threatened Percy with bodily harm if he didn't take care of his boyfriend, which left their boyfriend blushing furiously as he hid his face in his hands. Percy got flustered by all this because he had made some really good plans to make sure Nico had the best first time possible. The son of Hades had insisted that he understood how anal sex worked, but under duress he admitted that most of his information came from 'online stories' (at which point Percy groaned, "What sort of bad fanfiction are you reading, you dork?") and from ghosts roaming the Fields of Asphodel – which were way out of date.

So Percy spent the first hour or so of their night slowly getting Nico to relax and let his nerves go enough to start preparing him; when Nico finally gave way Percy took his time, conscious of how his boyfriend preferred to be touched. He'd learned though careful experimentation weeks before, when late-night kissing turned much dirtier and Percy pressed a finger inside him. Later, as he kissed a line down his boyfriend's stomach and over his ribs, he felt Nico's body practically vibrate as he twisted three slick fingers inside, gently massaging his prostate. When they finally came together, Nico held on to Percy like a blessed lifeline, his fingernails leaving long, raised scratches across the son of Poseidon's back as Percy slid into him, a moan escaping Percy's lips.

After a few moments Nico pulled on his arms, urging him to move, so he did; Percy had never done this before, and he easily got caught up in the wonderful sensation of being inside his partner and moving together like they were born for it, but Percy was in control enough to realize that Nico wasn't saying anything. He stilled, noticing suddenly that Nico had his eyes squeezed shut and that there were tears just in the corner of his eyes. Terror and nausea welled in Percy's stomach.

When he stopped, Nico frowned and looked up at him in confusion. Percy could tell that his eyes were still red and his lip was thoroughly bitten. "What are you . . ." Nico muttered, his voice strained as though he was talking through pain.

"I'm hurting you," Percy whispered, horrified. "Fuck, I'm sorry-"

He started to pull away, but before he could Nico's legs wrapped around his waist and tugged him close again with a grunt as Nico pulled him deeper. "Don't," the son of Hades hissed, wiping his eyes with his forearm. "Don't you dare. I'm not – you're not hurting me. I just . . . I'm really happy, okay?"

Percy traced his thumb under Nico's eyes, gently wiping away the last remainders of his tears before laying kisses to his eyelids. Happy wasn't a normal or common emotion that Nico dealt with, Percy acknowledged that. The fact that he was feeling that now meant the world to him. "Me too."

Nico doesn't scream during his orgasm so much as he scratches Percy's back deep enough to draw blood; when Annabeth arrived later and found her boys curled up sideways on Percy's bed, she smiled and traced the marks gently.

0o0

Nico was always a fast learner, and he wasn't afraid in the slightest to push Percy onto his bed and pin him there, lust-dark eyes boring into sea-green ones. Percy arched against him, twisting his wrists to test Nico's grip; Nico held fast, smirking down at his boyfriend with that nerve-fraying, triumphant leer.

Oh. Percy licked his lips. "I kind of like this development," he muttered, his husky tone betraying his arousal.

Annabeth walks in as Percy is crying out to the gods, trembling on his knees and elbows with Nico balls deep inside him, draped across Percy's back. They don't even realize she's there until the bed dips and Nico freezes, staring openly as Percy's girlfriend lies down on the bed beside them, her face propped close to Percy's.

He shuddered and groaned when he saw her, twisting his hips back onto Nico's cock.

"Go on," Annabeth said, her gaze flickering to Nico. "He's close."

Percy flushed as Nico growled a low "I know" and snapped his hips forward, earning him a whimpered curse; he tugged Percy's head back by his hair and bit his neck, hard. Annabeth's fingers tangled with Percy's against the sheets, but that comfort didn't reach her eyes: one brief glance into his girlfriend's eyes told him she was definitely enjoying the show. As Nico picked up speed she leaned in and described, in vivid detail how hot his boyfriend looked fucking him like this. She kept it up until Percy tensed and moaned into his forearm, body jerking in release, and Nico moaned low in his throat as his hips stilled, his fingers digging into Percy's hips. When he pulled out gently and collapsed on the other side of Percy Annabeth moved in, kissing the bite mark on Percy's neck and teasing her fingertip over his stretched hole, slipping her finger in with a helpless sound from her boyfriend.

"We should fuck him together," Nico suggested a few minutes later after regaining his breath, watching with fascination as Annabeth teased their boyfriend. "I think that'd be really hot." His fingers traced up the line of Percy's spine lightly, leaving goosebumps in their wake. That was new, coming from Nico.

"You two are gonna kill me," Percy groaned, his voice muffled by a pillow.

"Sweet death doesn't suit you," Nico teased, nuzzling the crook of Percy's neck.

"I think we can agree on that," Annabeth hummed, curling up with them so Percy was surrounded on either side by his loves.