Tam said: I don't think the misfit trolls came about because of bad breeding. They've just become especially single-minded and corrupt.
Yes, the Misfit Trolls weren't bred, they were created by the millennia-old pool of magic that created Madcoil and continued to linger and grw in Goodtree's Rest Holt until Sunstream destroyed it.
Remember, they were normal trolls when they discovered Ahdri's cocoon in the desert after the events of the Shards War and Forevergreen storylines. Searcher and the Sword happens just a few years later, and in just that amount of time the trolls devolved into the misfits.