for the wip game, toxic vigdagcup is calling my name, i'd love to hear about it!
My idea for that starts with Viggo and Dagur getting together, which involves Viggo manipulating Dagur, giving him more and more authority (and emotional and physical intimacy) so long as he does exactly what Viggo says, when he says it (which basically means being Viggo's personal body guard/attack dog/service top)
It's terribly co-dependent, which Dagur needing the only close emotional relationship he can get, and Viggo getting high off the adoration and obedience Dagur gives them.
Then enter a recently-kidnapped Hiccup, who Dagur and Viggo have fixations on -- except Dagur quickly realizes that he doesn't actually want to hurt Hiccup and has to choose between following Viggo's orders and hurting Hiccup, or not hurting Hiccup but being physically punished for it. Dagur chooses the latter and ends up getting beaten within an inch of his life by Viggo, at which point he finally decides that he's going to help Hiccup escape once he heals. And then the rest of the story is Dagur and Hiccup escaping from Viggo (and probably killing him) and Hiccup trying to figure out his complicated feelings for Dagur.