Why is this guy's face like this? Is there a story here?

I think he's just a drug addict. There isn't really any explanation for this in game or anywhere else, I've just seen others say as much and it seems to make the most sense.

This guy with the party outside of the temple where you get Withers, has the >!half-illithid !<texture on his face. Is there a story here? Something hidden? Or just a random reuse of that texture.

I read something once that said he was a half drugar and that's from him being exposed to sunlight for long periods. But until I can find more proof than a single reddit comment, I'm considering it just a theory.