Just a bit part because I think he would help make clear something to the reader that the characters in the story never know. Doesn't even appear on stage, but his attitude is one that doesn't make sense with what they know. Because things about them have been transformed, not quite neatly.
Then I think that bit part would be interested in other events. For the same reason that he made things clear, he would continue to be annoyed at things.
Unless I have another transformation strike.
Or if the transformation moves onward and makes him less malcontented as it smoothes over the edges. . . .