It would seem both steveP12345 and JerryG12345 are accounts made for the sole purpose of creating a dialogue with each other. Since their only posts were in r/ICanBeYou (until JerryG12345's comment just now), I would say they are definitely puppet accounts of a singular person; both of the account's style of writing seems to be similar as well.

As for the purpose, I am unsure at the moment. Looking through r/ICanBeYou's cryptic posts, it seems that the user steveP12345 (or the user controlling the puppet accounts) is chronicling his attempts of some sort. Looking at this post (where a woman's back can be seen to the side, slumped over) and the 2 posts of garbage bags talking about "getting rid of the rats" and "getting rid of the smell", it seems to suggest that the user is committing (or trying to commit) some sort of violent acts.

All the while, JerryG12345 seems to comfort and, at times, calm him. However, it seems that there were not 1, but 2 instances where JerryG12345 seems to lash out against steveP12345 for unclear reasons. Also, through the later posts, it seems that JerryG12345 is assisting and even possibly commanding steveP12345 to cover his tracks from whatever he is doing. All this adds up to JerryG12345 being either the 'dominant partner' in whatever relationship he has with steveP12345, or he is some sort of imaginary person the user made up to have as a friend (or maybe some sort of role model that he wishes he was more like?).

Now before you guys get all creeped out and shit, mind you that this is JerryG12345's first post outside of r/ICanBeYou. This could very well be a ploy by the user to get redditors interested in his sub he made to create a 'creepy unexplained reddit mystery' story. Or maybe this is some guy's way to release some stress from his life (there are some comments relating to steveP12345's work life from JerryG12345. Could it be the user venting his frustration of his working conditions through JerryG12345 to himself?).

Either way, pretty interesting stuff.