Don't break his mind. In his world, the only ones capable of changing one's species are witches, who are worshipers of evil and are to be avoided at all costs.
(I will not portray these kinds of people in UJ because they do not pertain to the story. Ash does know of them, however, and does not approve of their practices.)

If your method is non-witchcrafty, however, by all means! (all-powerful artist/author-ness does not count as witchcraft, btw :B )

#asklaceunionjack