Imagine if Eren had a twin. Whenever someone would say “Go fuck yourself,” he would strut over to his twin and threaten to do him there and then.
Or Levi would be looking for Eren, run into his twin and think it’s him. Just for fun, the twin would pretend to be Eren and piss Levi off at the end of the day by saying he isn’t the other brat.
Jean keeps accidently picking fights with the wrong person. He fumes when he loses only to see Eren sitting down and laughing with Armin