I only have vague memories of random details but here it goes:
Loki was imprisoned in a cave below the palace or below Asgard and it was sealed up with food delivered by magic I think. Anyway when Thor is shutting Loki in there Loki tells Thor he is pregnant and that they will both die if he leaves him down there but Thor doesn't believe him.
So because of the baby the food they send is not enough and I think he's starving. The cave had a water source and he managed to dig it out and find an underground lake or something in a connecting cavern
Loki eventually escapes months later and I think he eats a raw bird like immediately after lol.
Thats all I recall, but I want it!!!!
He might have gone to Midgard after, and I think maybe Heimdal knew but didn't tell anyone
Thanks in advance to any answers :)