Someone—he's not sure who, only knows their scent and not their name—brings him books.
They aren't supposed to, he knows. No one is supposed to. And sometimes no one does—bring him things, he means. Sometimes, he goes so long without things that his stomach aches and gnaws at his insides and all he can do is dream of the taste of anything.
He knows their scent, and he thinks they are kindest of his keepers—when they watch, he is given books, and food, and sometimes new clothes.
For this keeper, he will gift a swift and painless death. Perhaps snap their neck in one bite, or crush their head in a clean blow. Maybe even—when he is particularly generous, when a new book has just arrived and he fumbles and pours over the words, mouth and fingers sticky with honey cakes left with the book—he will let them live until they are old, and then kill them, before they grow too infirm.
The mortals still tell stories about him. They say he is the dangers of power unrestrained. They say he is strong, and he will occasionally flex the muscles beneath the silvery chain that ties him to the wall and think how if he were truly strong he would not be so leashed. They say one day he will escape, and that he will kill Odin Father, and sometimes—when his favourite keeper has been kept away and his stomach aches and he feels most mad—sometimes he can already taste the sweetness of Odin Father's blood on his tongue.
The mortals do not talk about what was done to Jormungandr. They do not talk of Asgard's treachery and the taunts, the teasing, whispers of bastard and mutt.
They do at least say how Asgard tried to trick him and chain him, and he still remembers the not-nearly satisfying enough crunch of Tyr's bones in his jaws.
One day, he thinks, he shall finish the job.
He does not think himself dangerous, for he is not. He will not attack unless provoked—but Asgard provoked and provoked and provoked and he will gladly tear them apart when he is free.
He wishes he were the one who swallowed the moon.
This—the promise of destroying Asgard—is the only way he finds he can forgive Da, Da who has a new family, Da who has forgotten him, who has not found him, who has never once stepped foot here, and were he to see Da, he might tear him limb from limb, and do it with great gladness, because it is cold, and he is hungry, and he has fury in him the likes of which only Nidhogg might understand. But when Da comes, he will bring the promises of blood and death and bones, and so he can forgive him, for now, long enough to focus outwards—and once he has tasted Odin Father's blood, then he shall taste Da's, and he dreams of how it will be the sweetest thing he ever tastes. Then, last of all, he will kill the kind one.
Swiftly, because he is generous.