Thirteen years ago, Loki ended up falling into a wormhole that transported him to the Sanctuary of Thanos instead of falling into space and dying like everyone thought. When he transported into the Sanctuary of Thanos, he met Thanos and the Other.
As soon as Loki realized he wasn't dead, he made sure to use his magic to shield himself from the eyes of Heimdall. He knew all of Asgard thought he was dead. He just thought it would be better for them to think he was dead in that moment. He committed treason when he tried to kill Thor. He knew he'd be put in the prisons for the rest of his life if they knew he was alive. That's why he let go of the scepter back in Asgard. He would rather die than be put in the prisons. But Loki had a new purpose with Thanos and the Other.
Loki has changed tremendously over the years. He became ruthless and angry all the time. But his love for Y/N never changed. Whenever he gets free chance he uses the scepter he was gifted to show him his memories with Y/N. Y/N is the only thing Loki truly cares about. The memories with her has been on repeat for thirteen years. When he thinks about the his memories with Y/N, he usually start from the moment they met to the peak of their relationship.
For thirteen years, Loki has been helping Thanos look for infinity stones. The first stone they found was the mind stone. For years after finding that stone, they've been trying to locate each of the other stones. Recently, they found out where the Space stone was. It was on earth. The Other made a deal with Loki to retrieve the tesseract, the space stone, and in return they will attack Asgard.
The Other: It it time for you to go to earth to retrieve the tesseract. In return, we will attack Asgard and destroy everyone and everything.
Loki: Not all of Asgard. Just the King of Asgard. Do not touch the Queen.
The Other: Understood.
Loki: Then it is time. If there are any complications in retrieving the tesseract, will the Chitauri army be ready for battle? I need an army.
The Other: You will have the Chitauri army if necessary, Asgardian. If you fail, our deal will be terminated.
Loki is ready for the mission to earth. He isn't ashamed of anything he has done over the thirteen years. He did what he had to do. He doesn't regret trying to kill Thor either way back when. They only thing Loki regrets in his life is not running away with Y/N. He left her behind. He feels guilty for that. Loki feels guilty that Y/N thinks he is dead as well. But no one could know he was alive, not even the love of his life. He always wonders how she is, what her life has been like over these thirteen years, and if her and Thor are happily married.
