(Yes, I'll be focusing on THW for now on.)
I was rewatching the movie with my little brother these days, and suddenly I had this idea.
I believe he would be older than the boys. Assuming they are 15-16 years old, Rev would be 17-18, also considering the fact that Larry mentioned: ''He was my disciple.'' So Rev would have worked with him in the garage in the past.
Now, for the final parts of the movie, I have two versions:
1- After Larry arrived at the hideout, Rev would reveal himself, and in fact, the two would have planned all of that, just so that the city would have the 4 boys as its heroes. Yes, Jerry would still steal the car.
2- Rev was the real villain, and he would have stolen the car just to bring chaos to the city. However, I like to think that at some point, he had a redemption arc and went back to working in the garage with Larry.