Rod has had about four or five origin stories over the years actually, but nothing has ever really stuck very well. I will say that Rod is one of the earliest characters in my writing–he’s the person “Losing Control” is being narrated to, by Micah (though he’s unnamed in that) and also a key character in “Sinful Revenge”, which is more of a direct sequel to “Losing Control”, and is the main antagonist in “Dangers of Smoking”! He’s all over the place, once you start looking for him.
These new Pigtown captions owe a good amount to @rbbrpigmen who revitalized and riffed on the idea as more of a neighborhood than as a bar, which is where this newer version of Rod is haunting.
As for his relationship to Pigtown–as far as canon goes, Pigtown has always existed, or at least existed before Ron (and Micah) got involved. Micah, in every version, is a wizard. Ron is a young college guy, usually an athlete of some variety, with some magical potential who gets involved with Micah, and then…<something something something>…Micah is “gone” (unspecified) and Rod then an older bear and the new proprietor of Pigtown, whatever Pigtown might be–I still don’t really know what it is myself.