As punishment for his treachery after the Convergence, Loki is stripped of his magic and his immortality, and imprisoned beneath Asgard. He is to while away the remainder of his life contemplating his crimes, and doing penance. However, fate has different plans.
Loki is kidnapped from his cell, and sold into slavery on the distant planet of Uundar, outside the Nine Realms. The cruel planet is run by the licentious, and vicious Commander Varic. Loki is branded with symbols denoting his crimes, and made to work beside other criminals. There, he meets a powerful, green alien, Carion; a dwarf of Nidavellir, Rotten; a Vanirian assassin, Yoric; and a Xandarian Nova Corp pilot, Rye. Together, they form a group over the need to survive, but it soon becomes something more.
Loki never wanted this. He just wanted to be left alone. But, life never seems to go his way. Now, he must fight to attain his freedom, and the liberty of all the slaves on Uundar. Criminal or not, sometimes bad guys are the only good guys.
Loki had committed treason on a level Asgard had never seen. He would not be welcome back to his home realm. He would remain at the mercy of those he tried to control: the humans, SHIELD, and, of course, HYDRA.
By the time the Avengers come knocking HYDRA's door, Loki's long gone in every sense but the physical. Fortunately, even in his silent, fearful state, he's managed to make some friends. Wanda and Pietro won't let anyone hurt him. The Avengers are nothing but a threat, and Ultron makes them a promise that they'll be free of those so-called heroes soon enough.
(Basically, it's an Age of Ultron au where Wanda and Pietro have adopted a very broken Loki and they're determined to keep him safe.)