"Come on Hiccup, just hit it a little," Stoic argued with his four-year old son. "Just enough for it to break."
Hiccup shook his head violently, refusing to hive himself a concussion.
Stoick had come to this particular part of the island because it was a great fishing place and had some small rocks. Perfect for combustion.
"No no no," Hiccup yelled after the fifth time his father, Stoick the Vast, tried to get him to hit his head against a rock his size.
"Troll," Hiccup giggled, and ran over to a tree, grabbing a long stick on the way. He started to look around the tree, searching for the troll he'd been sure had been there a while ago (it was a squirrel by the way).
Stoick sat down gruffly and put his hand up to his face.
"Oh Val, what am I doing wrong?"
Hiccup continued to giggle and slap the tree against the trees, trying to scare the trolls out to interrogate it.
"Where are you troll! What have you done to my left socks!?" Hiccup had been running short on left socks for some reason, or at least that's what he thought. To be honest, all his socks looked the same.
Stoick sighed. Then he chuckled at the sight of his son.
He'd try later again. Every time he took his son fishing he would try.
He got back to fishing by himself, catching two large bass and a dozen Icelandic cod, Hiccup playing in the background, breaking his stick and replacing it with another from time to time.
Stoick continued to bring his son to the same place to fish every year until Hiccup turned nine. Then he gave up the time to do his duty as a chief. The dragon attacks had increased and Hiccup seemed to be a lost cause after all.
That was the year Hiccup started his apprenticeship with Gobber, who somehow got into the whole idea that trolls existed, despite the fact that Hiccup told him it had always probably been a squirrel (but Gobber had stopped listening at that point).
Hiccup never caught the troll, though he became quite nimble to the point of not tripping over his feet anymore when he searched for one (take into account that he searched in a very rocky place filled with roots and holes). He used that to weave through the crowd of vikings every dragon raid.
Hiccup did almost catch one though. He could have sworn he'd seen a a green tail, but his father called out to him that it was time to leave, so he left and never saw the troll again.
And that's how Hiccup's childhood was spent (other than the bullying and scorn of the rest of the vikings, but you guys already knew that).
The End.