okay, I was watching HTTYD
and it comes to that line “three hundred years and I’m the first viking who wouldn’t kill a dragon”
and for sOME REASON I got this idea for a crossover AU in which Jack was part of the first wave of vikings to settle down on Berk but then he drowned on the lake from that cove where Hiccup trained Toothless
and for those three hundred years he traveled the world but would still always come back to Berk (“It snows nine months of the year and hails the other three”; “Winter in Berk lasts most of the year. It holds on with both hands and won’t let go”)
and he sort of established himself as the legend of Jokul Frosti, but never not really enough for anyone to see him
and then Hiccup was the first person in three hundred years to see him

IT GOT BETTER