Brother

A Brother is God's one and only mistake in this world. He could've just stuck with Adam and Eve and left it there, but NOOOO, He said "Go unto the world and be fruitful." And then He just had to tell Abraham "Ye shall have descendants as numerous as the stars." Apparently he left out "Oh, and ye shall also have to bear the burden of a male sibling."

Behavior

"Normal" brothers have quite a tendency to have immense amounts of resentment toward his other brother, especially if said brother is older and smarter and more knowledgeable and more personable and better at everything than the other. This brotherly resentment always leads to ridiculously immature name-calling ("Dumbbutt!" "Dickweed!" "Shithead!" "Poser!" "'Tard!" "Whore!" "Butt-sucker!" etc.) that often does not go unheard by parents. This usually transitions into a game of "murder-punchies," a game of brotherly bonding hatred played in a shared bedroom in which the goal is to make the other brother say "I formally give up to you, brother of mine, for I am a pussy and you are my god" by continually punching each other in the arms and the abdomen.

On the other hand, "abnormal" brothers display immense amounts of respect and maybe even admiration for each other after being "formally housebroken" by their parents. They actually cooperate with and help each other in most, if not all situations. And the most shocking parts? Both brothers actually behave with etiquette in public, and if a brother actually does something wrong, that brother takes full responsibility for it!