Born and raised into the Nutter tribe, Chadd Nut was raised to be a strong nutter. IDK I didn't really look at the lore stuff. He survived his nutting trial and they were like "BANNED". And he was like "FINE. AND I'M TAKING THIS WITH ME. AND THIS." As he left with a coconut impaled on his horn and grabbed a giant coconut crab on the way out.
After exile he wondered with his coconut trophy and petty giant coconut crab that he took with him out of pettiness. Bumping nuts with Twig was how they met and seeing that he concussed her he knew they were meant to be.
He is an asshole to everyone but Twig, she is the exception. Just like Christina with everyone but Mabel in real life.