I hink anyone could imagine a Wemic treated as a wild animal, caged, tortured, and abused from birth becoming evil... The question that springs to my mind is wheher he would ever seek to serve anyone -even a god- after that, or he would turn into a rampaging murderer seeking out all those of the race that had abused him. Although many would see such a Wemic hunting Dark Elves as a good thing... It might work better if some uninformed villagers found him as a cub beside his dead mother (what killed her is unimportant) far from the usual haunts of wemics, took him home, chained him up as a watchdog, fed him scraps, beat him to force obedience and to make him vicious enough to keep intruders well away, and generally abused him all his life until the night he found a rusted length in his chain and managed to break free. He might still wear the welded collar with a length of chain dangling from it.
Even more interesting, if the village (now deceased to the last child) had included not just humans but some other group such as gnomes or dwarves (most elves would not tolerate such treatment of even an animal)... Now he is hunting not only humans but the other group as well. Because he is paranoid, he hunts with great stealth, makes sure of the odds before an attack, and strikes like a berserker.
Problems are that there would be few, if any role play opportunities. Such a creature could never be induced into the strongholds of his enemies even in disguise, lest he be recaptured. He would never risk that.