Red is a short-tempered person. The angriest of all the birds, he is not above using violence when someone annoys him. He is someone who takes his duties very seriously, not willing at all to leave them aside. However, he also likes to discover new things when he is in a day off.
During his earliest years, Red was an antisocial person who was rejected by the other birds. With an unstable anger (despite him trying to state otherwise), he had always hated being disrespected and made fun of, as he took jokes very seriously.
This would result in him getting enraged and/or sad. As he grew up, he also became someone who could get frustrated by anything, acting rude in front of other people not matter how friendly they were towards him.
However, after he stopped Leonard from cooking the eggs from Bird Island, Red became much more outgoing and was approved by the rest of the birds, which allowed him to control his anger issues much more than before. Nevertheless, even after these incidents, it was shown that Red could still get angry at anything, sometimes cursing himself for his actions, and showing an open hatred for ridiculous holidays.
