Breaking the Habit

Despite having many chances, Loki didn't flee. He did not leave his brother or his people to perish while he escaped. He knew that when Thanos found him, his life was forfeit. His fate was sealed the moment that he failed to retrieve the Tesseract years ago. No tricks, no illusion, no lies, and no last-minute escapes. He couldn't save himself this final time.
Thor failed in so many ways. He failed to protect his people. He failed to save Heimdall. He failed to stop Thanos from murdering his brother. And then he failed to kill Thanos and half the universe was lost as a result.
When they failed to stop Thanos and so many lives were lost in an instant, Tony was powerless. He could only watch as the teenager who should've never been halfway across the galaxy dissolve in his arms. There was nothing that he could do. But when he and Nebula, in their attempt to limp their way back to Earth, find the site of a destroyed vessel floating in the middle of space with the bodies of the Aesir drifting in the vacuum, he remembers enough from Bruce to realize what they'd found. And he sees one face he recognizes and comes to a grim decision.
Sometimes you can't save everyone. But you can sometimes save someone.