Basically, an old friend of Odin’s is in Asgard and mentions his interest in Loki and so Loki ends up having to marry this old, decrepit King from like Alfheim or maybe Vanaheim. The king has two or three grown sons who don’t like their father. The king has killed his old wives before or drove them to death, something like that.
Loki does his duty like a good son, believing the old king will croak any second but like hundreds of years pass and the old king is still kicking and Loki is suffering for it.
The old king’s sons form a parental-child like bond with Loki, turning against their father to save Loki.
Thor goes to the Norns to ask to save Loki’s life and there’s a string or something that he tampers with to save him.
I believe there is also a sequel (maybe not completed) where Odin is having visions of these slimy ink like things. Like, Odin is now suffering all the horrible things Loki did while with the old king.
I also remember this like torture device thing kinda like the rack that the king would use on Loki and when Thor finds out about it he uses his thunder to melt it down to nothing.