Summary: Sometimes when Astrid touches Hiccup, it's very nice. And sometimes it's really, really annoying.
Astrid, Hiccup finds, gets bored very easily. He wouldn't have suspected that. She seems so focused most of the time that he assumed she constantly had something occupying her mind. He was wrong though. Astrid is incredibly focused when she's training, or fighting, or flying, and maybe that was the problem. When she didn't have anything else to do, and there wasn't an axe nearby to be sharpened, she found something else to occupy herself, usually something random.
Since Hiccup spends much of his time around her these days, this "something random" often takes the form of "something to Hiccup." So far she's braided his hair, stolen the tie holding the top of his shirt closed, and somehow managed to dismantle his leather harness, which he hadn't even noticed until it had fallen off of him. After that incident he learns not to let her stand behind him when he's otherwise occupied.
Today, he forgets. He's talking to Snotlout, and apparently Ruffnut has wandered off and left Astrid with nothing to do, because she idly touches the small of his back with her index finger, then quickly trails it up his spine.
Hiccup's back instinctively arches, and he squeals in a distinctly unmanly manner before jumping away. The touch had almost tickled, except it was much stronger and shot out to every part of his body. Snotlout is laughing, and Hiccup whirls around to see Astrid looking surprised, then pleased and amused.
"Don't do that again," Hiccup says.
She does it again. Every single time Hiccup shrieks in a way that sends his friends into spasms, and instinctively leaps away. It's a reflex, he thinks, because he certainly can't help it, and he doesn't get used to it either. Astrid -- and everyone else in the vicinity -- is terribly amused by this response. Annoyed, he waits for her to get distracted, then tries it himself. Astrid merely turns and gives him a look and a little smirk. Of course. Hiccup would be the only one to react to something like that with his best impression of a six-year-old girl running from a mouse.
It's annoying, but it's only one thing, and most time spent with Astrid is thoroughly enjoyable, so he puts up with it. Most of the other touches they share are very nice, anyway. He can put up with the punching and pushing and tweaking because everything else is more than good enough to make up for it.
One night, Astrid is in his bed, naked and sated. Hiccup is gently tracing the lines of her body, not really looking to start anything else that night, but just enjoying the feel of her. He runs his finger across the small dip where her hip meets her thigh, and she gasps and jerks, violently.
For a second they stare at each other in shock. Then Hiccup smiles, and Astrid scoots away.
"Don't do that again," she says.
"Aw, why not?" he asks, still with that shit-eating grin, and makes to reach for her again.
She sits up and moves further away. "Hiccup, I'm serious. I will hurt you."
"You're going to do that anyway," he says, moving closer.
She shifts back again, intent on increasing the distance between them. "This is about the back thing, isn't it? Look, I-I'll stop if you stop."
Hiccup pauses and lower his hands. "That sounds fair," he says, and Astrid breathes a sigh of relief. "But, you know, we're not exactly even yet," he adds, and reaches for her again.
She quickly shuffles backwards. "Hiccup, doooooOOOOOH!" she shrieks as she falls off the side of the bed.
Hiccup can't help it. He starts laughing. He's going to get in so much trouble when she rights herself, but right now it's the funniest thing he's ever seen in his life.
Astrid's head pops up, and she literally growls. "Wait wait!" he gasps as she tackles him. She's angry, but not really, and soon enough they've started touching again after all.