Author's note: This is hopefully the first of several The Last Olympian inspired fics to come out of me this summer. This fic ran away from me a few times during the writing process, and I've finally got it back to the way I wanted it to be when I first started brainstorming. Some fluffy Percy/Annabeth to celebrate the awesome that was the ending of The Last Olympian.

Warnings: Major spoilers for Percy Jackson and The Last Olympian. There's also some sexually suggestive content, but nothing explicit.

Disclaimer: I don't own Percy Jackson and the Olympians.

Invulnerable and Invincible

There are a few things Annabeth Chase likes about having an (mostly) invulnerable boyfriend.

For one, she doesn't have to follow him around during battles to make sure his seaweed filled head isn't getting chopped off by the latest monster of the week any more. She's seen enough weapons break against his skin to know it's just not sheer dumb luck or the thickness of his skull protecting him now.

But she looks after him anyway, because knowing that idiot, he'd forget that his back is his greatest weakness and leave it wide open for attack. She's had Percy's back since the beginning, though, so it's not like this is anything new for her.

Being the only invulnerable demigod in a few centuries also gives Annabeth new teasing material. "Seaweed Brain" will never get old, but it's become more of an endearment than a scathing insult. She likes to mock him about all the trouble his invulnerability causes, especially after he gets banned from playing Capture the Flag at beginning of the summer.

At first, all the cabins (even Ares) fight over whose team Percy would be on because he's the perfect player. He could just waltz into enemy territory, grab the flag, and then waltz out unharmed. But then everyone quickly realizes how unfair and boring having Percy on any team is and the Hephaestus cabin stages a revolt in protest of their dramatically increased workload, thanks to all the weapons broken on Percy's untouchable skin.

Clarisse is on her third spear in a month when it is decided that Percy would get his own team and would only be allowed to pick a handful of campers each game to make it fair for everyone else.

The invulnerable hero of Olympus sulks about the decision for weeks, and Annabeth delights in teasing him mercilessly about it at every moment. Percy quickly comes up with a few … convincing methods to keep her taunting to a minimum, which Annabeth enjoys much more than teasing anyway.

She also likes that Percy has to take several naps a day to recharge his strength.

Well, she thinks it's horrible that the River Styx takes so much strength out of him, but she enjoys the peace and quiet she gets while he's napping. He's hardly left her alone since she got back from visiting her family in San Francisco at the beginning of the summer. Not that she really minds spending time with him or anything, but she has a job to do as Olympus's official architect and she can't get that done if her lips are attached to Percy's all day long.

His naptimes became her work times and it suits her just fine, until Percy decides he wants to use Annabeth as a pillow while he sleeps. She almost tells him no, but it's already hard enough to get him to do it without complaining because he thinks naps make him look like a baby, even though he's sluggish and cranky as Hades on the days he decides to forgo one. Besides, she notices he has fewer nightmares when she's around.

So she tells him its fine if he puts his head in her lap, so long as he doesn't drool on her jeans, and no, it really doesn't bother her when her leg goes to sleep after awhile, and yes, Percy, she can still get work done when he's snoring away so he better shut up and close his eyes already before she does it for him.

She lies a bit on the last one because it's really hard to get any work done when he's in her space like that and she doesn't have room to design, short of using Percy's head as a desk. Plus she doesn't want to risk getting drool marks on the blueprints she has to give to her mother.

But she feels like a normal teenage girl with a normal teenage boyfriend every time she finds herself sitting under one of the tall oaks on a bright summer day, absentmindedly stroking Percy's dark hair as he dozes and she reads a book, so she lets it happen more often than she should.

Normal is such a nice, new feeling for her and – even though she doesn't think she'd want to be normal all the time – she thinks her mother or the other gods wouldn't begrudge her for putting off her work to enjoy it. Sometimes she gets so lost in the feeling that she forgets herself and falls asleep right beside Percy.

That habit, however, is thankfully short lived once Percy wakes up before her and starts teasing her for her snoring.

She can't even punch him like she used to every time he brings it up and he knows it all too well, which is something she doesn't like about his invulnerability. Percy's head got much bigger once he came to camp for the summer – Annabeth's constantly surprised he can walk without falling over from the weight of his ego. She supposes her head would be pretty huge too if she was a sixteen-year-old boy who had saved the world and was (mostly) invulnerable, but just because he's the best warrior at camp doesn't give him an excuse to go easy on her and treat her like she's not even worth his time during training.

During one exercise in July, she gets so frustrated by his attitude that she decides to remind him that he does have a weakness after all and she raps him sharply with the butt of her blade at a certain spot on his lower back. Her victory is short lived when Percy lets out a strangled yell and drops instantly; Annabeth panics, thinking she killed him in a fit of annoyance, but Percy turns out to be fine, waving off her concerns by saying the blow had surprised him because he hadn't felt pain in so long.

It doesn't stop her from apologizing profusely to him, even when he gets annoyed with her, or make her stop feeling guilty for abusing his trust in her. She was the only one in the world who knew his secret, and she had used it against him without a second thought just to get back at him. She could've killed him if she had used more force or… or …

Knowing Percy's weak spot terrifies her beyond measure. It's a huge responsibility, and sometimes she doesn't think she handle it. She doesn't understand why he would give her that kind of knowledge; her fatal flaw is her own pride, for the gods' sake! She has so much power over him, knowing what she does, and it's always a temptation not to do anything with that power.

She asks him a few days later (after the guilt nearly drives her crazy) how he knew she could handle that knowledge. Percy – that stupid, simple seaweed brain – looks at her like she's the idiot and says, "It's you, Annabeth."

Annabeth doesn't understand how that's supposed to be an answer for anything, so she decides to prove to both him and herself that she can use her knowledge of Percy's weak spot for good. She starts thinking of ways to do this, and ends up coming with some absurd theory about the sensitivity of that patch of skin.

It doesn't seem too absurd when she tests it during one of their heavier make out sessions. While he's kissing her, Annabeth slips her hand up the back of Percy's shirt and strokes gently over that little spot. She feels him tense against her and then his breath hitches, so she strokes a little slower. Percy bites his lip, his eyes closing momentarily, and Annabeth does it again.

And again.

And again, until Percy's panting against the crook of her neck and shuddering in her arms. Annabeth's a little embarrassed that a simple bit of stroking led to that, but when Percy recovers and looks at her like she's some kind of goddess, her embarrassment disappears and Annabeth finds she quite likes having that kind of power over Percy.

While that's nice – all right, it's much more than nice; it's downright amazing – it's not her favorite part of having an invulnerable boyfriend.

What she likes most of all is the feeling she gets whenever she touches that spot in the middle of Percy's back. It doesn't matter where they are – walking down the streets of New York, by the lake at Camp Half-Blood, in one of their cabins – or what they're doing, it's always the same feeling.

When she touches that spot, she feels Percy. The warmth of his skin, the beat of his heart, the strength of his love… Everything that makes him who he is is centered in that tiny patch of skin, and it anchors him to her and the rest of the world. Percy is her other half, the one thing in this world that makes her human and whole.

He doesn't need to promise her that he won't hurt her because she feels it in his touch. He doesn't need to tell her he's her family because she already knows he is. He doesn't need to tell her that he loves her because she knows that too.

Percy may be invulnerable, but as long as he's by her side, Annabeth is invincible.

And she's pretty sure there's a few things he likes having an (mostly) invincible girlfriend.

Thanks for reading. Your reviews are greatly appreciated.