it's simple to me. Stepfather wants son to be responsible, to learn responsibility. Son has asset and wants to maximize the value and growth of the asset. Pay up or move out, dear stepdaddy.
It sounds like stepdaddy is a gold digger looking for a free ride to start with.
yeah, stepdad goofed when he seemed to think "dumb teenager" doesn't understand how houses work, probably just assumed kid didn't know that there wasn't a mortgage that he (or mom) was paying. Though, I guess the mom was paying it and maybe stepdad was even splitting it and just never asked or had any understanding anyway to clarify the ownership.
seems...dodgy to not understand that after getting married.
anyway, at the end of the day, dude went into battle with terrible information and even worse: a stupid brain with no cards to play, and now is trying to backpedal in the worst way. I'd be curious if he actually was splitting the mortgage and didn't know the deets, or he was seriously paying nothing and thought he could exploit the kid for some free cash that would only be going into his pocket.
..the weird bit is the kid just turning around and asking stepdad and his mom to start paying him--is there actually no mortgage and it's just property tax? Has mom been paying the mortgage all along anyway, and it's just a formality and simple arrangement that never was an issue between them? If the latter, then the kid doesn't have much leg to stand on, because it's not like he's paying the mortgage with no job.
....but depending on circumstances of dad's death, the family could have gotten some sweet death insurance from the mortgage company that wipes out something like 60% or more of the remaining principle? (I guess it depends on where they live--but some of these are really generous and depending on your zipcode, can pay off nearly all of a mortgage)...so that's another situation that could make the house pretty much paid for, and this dumb stepdad in a really bad light, assuming that's the case.