So basically, the power that be never really explained why Tavros sucks as a troll, or how he can even have that sort of personality in his society and still be alive.

I have this whole thing built up where the trolls basically take after their lusus, the custodian monster that raises them in the place of any parents. The ornery Cancer troll has a bad-tempered lusus he battles constantly, the predatory Scorpio who backstabs her own friends was raised by a giant spider with a taste for young trolls, and so on. Tavros' lusus is a tiny bovine fairy with a gentle nature, and in my head he sort of imprinted on Tinkerbull and emulates him.

I am such a nerd.