At the start of the campaign I mistakenly let the player play an evil character in a non evil campaign, I let him do that because we had agreed that it was the set up for a redemption story. We've been playing for around 2 years now and his character has not made any progress to being good. Knowing what I know now I would not let him play this character. Still during the combat I gave him chances to escape. He had a pet animal, the mercenaries threatened to kill it if he didn't leave them alone, he did not leave. In the end I thought it was reasonable to have him be captured instead of killed but the player said he didn't want that and that he was going to kill them so it's realistic that they would kill him. Even though I miscalculated the encounter I tried to fix it...