Even taming a baby one never does much for softening its wild instincts. Taming an adult animal is far more trouble than it's worth. Part of the cause of this is simply that animal sidekicks are really adorable (and loyal wild animal companions are cool in themselves), but most of the more interesting ones are not of domesticated species, and the only rational way for the hero to get one is from the wild.

Being a Friend to All Living Things can help, but surprisingly often it seems like nearly anyone can calm down a wild animal. Is a bear rampaging through town? Just give it some honey and it will snuggle on your lap. When animals do get mad, they're usually easily calmed down if just given whatever MacGuffin is necessary. Those hilarious Plucky Comic Relief chimpanzees and their hilarious antics? Never once do they get violent, no matter what (they may get mad for the hero's benefit, though).

In fiction, wild animals rarely act the way that they do in real life. Cracked, The 6 Cutest Animals That Can Still Destroy You

Pets wild at heart tv tropes