Oh boy, he would not respond well, at least not at this point. He isn't the kind of guy who can easily wrap his head around something so existential as being a fictional character, so that would throw him through a loop, especially as it would lead him to the zillion versions of him that have been created over the years. Plus, he's still half-convinced that none of this is real and he has actually gone crazy, and that would definitely make him even more sure.

All of that said, the more time he spends in Darrow, the more he is going to get used to the idea that everyone is probably fictional in some universe, and eventually such a discovery would be much less traumatizing. He'll still be weirded out, but he will get over it. He'll just be left wondering why he doesn't get to look more like Jude Law. XD XD XD