Yes yes, he's a "regular" deer.
Smog hasn't the slightest idea of his past in the world of the living.
How did Smog get stuck with his? Well you know how as a kid you get told not to feed the wild life? Yea, well they forgot that rule and fed Jeffery a body they were trying to get rid of so now they are kind of stuck with him. Luckily he stays at their actual home for the most part and is a pretty good guard dog that keeps intruders away... well he mostly just eats them, but it all works out the same.
Jeffery will be properly introduced a little farther along in the fanfic, but will get at least one or two mentions before he shows up.

Link to fanfic: https://archiveofourown.org/works/5.....ters/137964577