It was cold in the chamber, but Loki didn't mind it. After all, he still had on his five layers of armor from when he attacked New York with his Chitauri army. He had just finished reading To Kill A Mockingbird, and placed it on the stack of 20+ Midguardian books he had already amassed. He had just conjured another book, titled The Giver, when the doors to the room surrounding the cell slammed open, sparks from metal against metal flying around the room. Loki begrudgingly looked up, knowing exactly who was about to enter.
"You idiot!" Thor boomed, his face as red as the blood that soaked through his armor. Where Loki had stabbed him earlier, actually. "How could you have done something so injudicious?!" He came to a stop right in front of the two-way 'glass' the chamber was made of.
Loki suppressed a smirk at how angry he had made his 'brother.' "How could I have done what?" He feigned innocence, eager to see how far he could push Thor.
Thor slammed his fist against the glass. "Dammit Loki!" Lightning sparked from his fingertips. "So many innocent people died! You caused so much death and destruction! For what? Glory?"
"No, brother." Loki sighed quietly, but maintained composure. "I did it for reasons that you will never understand."
"I want to understand, Loki! Explain your reasons. Because if you don't, you will be executed the moment we set foot back on Asgard!" A small tear formed at Thor's eye. "That's the last thing either of us want."
Loki stood abruptly, anger burning behind his eyes. "That is a lie! You and Odin will prosper without my presence and rejoice as the flaming arrows engulf my casket during my funeral." Loki took a deep breath. "I did it because I had no choice, just as I had no choice in being taken from my home as an infant; just as every other action I have made in my life. You do not understand because you cannot understand. You have been handed everything you have ever wanted since your birth! You are the Prince of Asgard, and I am no more than another one of Odin's relics he obtained during a conquest." Loki turned his head. "I had no choice but to attack Earth. If I hadn't killed a couple hundred humans on a planet with more than a billion of such, the consequences would have been untenable."
Thor's face shifted from anger to pity to confusion during Loki's speech. "What consequences, Loki?" Thor asked quietly. "Who made you do this?"
Loki sighed, defeated. He was going to lose either way, sooner or later.
Might as well go out as a hero.
"Loki." Thor pressed.
Loki turned, a single tear running down his cheek. "If I hadn't waged war on Earth, Thanos would have completely eradicated the Asgardian race before any of you knew of it."