A/N: So it's my birthday today, and I felt like doing blue-related things. I honestly didn't know if I was going to finish writing this in time to post as I've been working on it a while since the bunny hopped into my head last month when I was baking cookies for my friend's birthday. (Yes, blue M&M cookies. And yes, I was sorting M&M's, which was the inspiration for the fic.) But then the last bit that was evading me came together and voilà! Fic to share! Be warned, though, it's high on fluff but low on plot.

A Blue Secret

OoOoOoOoOoOoO

Plink, plink, plink.

The unusual noise coming from behind Annabeth's room door makes Percy halt on the landing, his brow furrowing with curiosity. It sounds like quarters being deposited into a coin bank. Or maybe a wonky percussion instrument.

'Annabeth?'

The sound stops abruptly and is followed by a quick rustling noise and a loud thump. Then footsteps, and Annabeth's door opens.

'Percy! What are you doing back so early? I thought you and Frank were organising the Pyrrhic War re-enactment at the Coliseum today?'

'Oh, well, it had to be cancelled. Some junior legionnaire fed Hannibal peanuts. No war elephant equals no elephantry display.'

She looks at him a little blankly.

'Hannibal the elephant? He's peanut-intolerant. Huge mess—Frank's sorting it out now.'

'Oh, right. I forgot.'

'So what are you up to?'

'Nothing, just studying.' She looks away from him when she says it, to the thick tome of a textbook sitting open on her desk. He has the strange suspicion that she actually pulled it out right before she opened the door.

But he can't think of a reason why she would lie about it, and he has a feeling she won't take it well if he says the first thought that pops into his head, which is, 'Didn't sound like studying.' He doesn't want to be the suspicious boyfriend, after all.

And then he's distracted by Annabeth asking if he wants to join her. He says yes, of course. She picks up the book and moves so they can sit together on her bed. As he plays with her hair and listens to her talk about structural supports and Doric columns, he forgets about her mystery activity.

OoOoO

He is reminded a few days later, though, this time when a freak thunderstorm puts an end to his plans to go canoe-surfing in the lake with Piper (thanks a lot, Zeus, or Jupiter, or whichever form he's meant to be for a Greek demigod living in New Rome) and he gets home to hear the same steady plink, plink, plink coming from behind Annabeth's closed door once again.

He knocks this time and there's the same abrupt pause, the rustling—maybe a drawer opening and closing? Annabeth opens the door and this time he notices the little details he overlooked before: her eyes just a bit wider than normal, her breathing a little too fast.

'You're back!' She glances at the window and the weeping skies outside. 'Oh. I guess they closed the boating docks.'

He decides to be direct. 'What was that noise?'

The furtive expression that passes over her face is so quick, if Percy wasn't on the alert, he would have missed it.

'What noise?' says Annabeth, a little too casually.

'You know, that, er, clinking sort of sound.'

There's a moment's hesitation, and then she says, 'You mean the rain?'

'No, I thought I heard …'

She cocks her head to one side. 'Sounds like the rain to me,' she says with a shrug. She gives him an affectionate peck on the cheek as she passes him, heading for the bathroom. He catches sight of her fingers by chance. They are stained with multiple colours, like rainbow ink stains from different pens.

When she emerges from the bathroom a minute later, her hands washed clean and smelling of lemon soap, Annabeth launches immediately into a complicated narration about the interior design she's sketching for a temple Jason asked her to help with. This isn't exactly atypical for her, except that she usually waits for him to ask first before going all Alex Dunphy on him. It's almost as though she's trying to steer the conversation away before he gets a chance to ask questions she doesn't want to answer.

Yeah, he thinks, she's definitely hiding something.

OoOoO

He begins to notice a pattern. It's always when he gets back at an unplanned time—earlier than expected, cancelled plans—that he finds Annabeth holed up in her room doing whatever it is that she's not sharing. She's doing it only when she knows he'll be out of the house.

This conclusion makes him uneasy. It's not that he doesn't trust her, or that he thinks she's up to something shady. If there's one thing he's certain of, even more than the fact that pizza makes the best dinner and blue makes food taste better, it's that his girlfriend always has his back.

Besides, this is Annabeth after all, the girl with a million projects on her plate, most of which he doesn't even understand when she does tell him about them. It's probably just a new hobby she's picked up—maybe sewing; it did sound like she might be rustling through buttons in a bag. Except Annabeth is probably the least domesticated person he knows, so he can't really picture her hunched over a needlepoint. Or it could be—there's some brainiac game that involves chucking marbles in a wooden board with holes, right?

No, the fact that Annabeth might have a new hobby doesn't faze him. What he doesn't get is why it has to be a secret. She's trusted him with everything since they were kids: her problems with her family, her deepest fears, even her embarrassing crush on Gregory Peck that she swears she'll kill him if he ever tells anyone. There's nothing she's ever needed to hide from him. Except … well, except for that stuff with Luke, ages ago.

But that was before they got together. Back when there was a war with the Titans and they all thought he was marked for death by prophecy.

Gods, he hopes it's not some new war-related shit. Haven't they done enough with the Titans and then Gaea, and that whole debacle with the Norse gods that he still doesn't understand. Oh, and not to mention Apollo and his Roman emperors?

He goes so far as to ask her how she's been occupying herself when he's out, but she only raises her eyebrows and says, 'Are you suggesting I don't have important stuff to do that don't involve you?'

He wisely backs off from that line of conversation.

Still, he wishes he knew. The curiosity is starting to drive him a little crazy.

One morning he comes out to the kitchen to find Annabeth sitting with her elbows propped on the table, looking like she's waiting for him. He frowns, confused. Has he forgotten something? It's too early in the day to figure it out—at least he can't really think clearly before he's had some coffee, which thankfully Annabeth has brewed. He makes a bee-line for the pot on the counter and takes a huge gulp before facing her.

'Um,' he says, running his fingers through his hair. He notices she's wearing an oversized Camp Half-Blood t-shirt (probably his, which always turns him on way more than it should) and her pyjamas shorts underneath, so obviously she's not all ready to leave the flat or anything. That's good—it means he hasn't forgotten a morning date.

Then he sees the jar sitting on the table in front of her. It's one of those giant jam jars, about the size of a football, with clear glass all around, and it's filled to the brim with M&M's.

With blue M&M's, to be exact.

It all falls neatly into place then: the slow clink of tiny chocolate pieces into a glass jar, the rustling of candy packaging and fingers rifling through a colourful packet. The secret that was driving him crazy the last two weeks is sitting as a big blue present in front of him and he feels like a real idiot not to have put it together earlier. Between being distracted by Annabeth's mystery activity and how different spending summer summer in California has been, he's managed to forget that today is his birthday, which probably means that he's going to be in a world of hurt since his birthday is also conveniently their anniversary.

Well, there's a reason his nickname is Seaweed Brain and not hers.

'Well?' says Annabeth, her impatient tone at odds with the way she's chewing her lip. Annabeth is always brusque when she's nervous. Although why she would be nervous, he has no clue. She's the amazing girlfriend who made him a thoughtful gift. He's the dork who's failing as a boyfriend.

'I—wow. You did this ... for my birthday?' he manages to say, feeling every bit like the kelp-head she likes to call him.

Annabeth shrugs. 'It's your first one away from home, so I thought you'd like ... well, I would have done blue cake or cookies, but you know me and baking. I didn't want to burn the house down. This seemed safer.'

'Geez, Annabeth, you must have gone through tons of packets!' He can't really guess how many M&M's are in the huge jar—he never was any good at those guess-the-number-of-jellybean games—but she would have had to go through ten times the number to sift out that many. He pictures her sitting at her desk, patiently rifling through packs of multi-coloured M&M's. He can't imagine doing it himself without getting distracted and giving up.

Percy puts her arms around her and squeezes her tight. 'You're the best, Wise Girl,' he murmurs against her hair.

Annabeth relaxes into his embrace. 'I know. You're not so bad yourself, Seaweed Brain.'

They don't say I love you; but then, they've never had to.

OoOoOoOoOoOoO

A/N: For anyone who didn't get the Alex Dunphy reference, she's a nerdy character on the show Modern Family. Let's just assume Percy watches, yes?