Fellatio

Astrid pushed Hiccup in his back.

"Astrid?"

"Shut up," said Astrid.

Her hand rubbed against the front of his pants. She felt his thing harden, fitting her palm, before tugging his pants down, revealing it for all its size and girth. His head leaned back in his pillow and gasped as she stroked him, revealing the head through the foreskin. Without hesitation, she took the head into her mouth before trying to fit the rest of it, barely getting halfway before hitting the back of her throat. She got used to the odd bitter-salty taste before she took it in and out of her mouth.

Hiccup couldn't do anything except put a hand onto her scalp and moan at she pleasured him.

If she were dumb enough to tell anyone that Stoick's son, Hiccup the Scrawny, was hung like a horse, they would laugh in her face and call her a liar. Being Hiccup's thrall and roommate, she has seen it enough times when she walks into him changing his clothes or when he was bathing.

At one point, she had to sit alongside Hiccup as Stoick had given them the "birds and the Bees" talk and she tried doing the math about how something like Hiccup's cock was supposed to fit inside of her.

When Hiccup confessed that he loved her and the two started dating in secret, she started looking at it at different way. The two of them would exchange little anecdotes of affection throughout the day, and Hiccup would take her out to Raven's peak for picnic dates.

And of course, living together, their eyes wandered to inappropriate territories.