What I remember: Thor ended up capturing Loki and bringing him back home. Odin cannot let his deeds go unpunished, but neither does he sentence him to death. Instead, they lock him up in this tower/place he cannot leave. Loki conducts a plan and slow begins to starve him -- people rarely visit him (Thor, mostly, but I believe he's back on Earth). As long as the tray of food is empty, it won't arouse suspicion.
A long time passes and with no one else for company, Loki makes friends with a bird. Eventually, Thor comes back and through some event (I can't remember what), he ends up killing the bird accidentally (unaware that it meant so much to Loki). He's also horrified to see how think Loki has gotten.
He brings Loki to his father and a hospital like place (there may be something more wrong with him -- maybe he jumps from the tower?? I don't remember), but Loki refuses treatment and the nurse refuses to do anything to Loki against his will as part of her oath -- even if that means Odin's wrath. Everyone gathers around Loki to watch him die and Odin, Frigga, and Thor beg him eat/allow himself to be treated.
Loki refused to do this because what's the point if he cannot be free? He would rather be dead then trapped in a gilded cage for the rest of his life. It gets to just moments before his death that Odin finally agrees to free him if he would just eat from a golden apple (I think) and heal/live. Which, basically, was Loki's plan all along. And he does so. I don't really remember much after this.
Can anyone please help me find this fic? I'd really appreciate it! <3