Well, Red Avenger is pretty simple, and I figured I that would be a pretty good quality in a nickname. I kinda like it so I might just keep it that way.
I do like the name Scarlet Crusader, though. And Crimson Knight. I might change it to Red Scarlet Crimson Avenger Crusader Knight!
Or just the Scarlet Knight. Or Crimson Crusader. That last one's alliteration!
I'll roll a 6-sided dice later to decide. Thanks again, Randomizer.