My wife has two sons, one doesn't live here anymore, the youngest still alternates a week with us and a week with his dad, by choice. He's old enough he should be able to stay where he wants. Really good kids. I'm lucky that they're not little assholes. They're polite, easy to get along with, and smart guys. Oldest is going to technical school for electrical work, the youngest is in college, aiming for civil engineering.
Actually it would be kinda sad if I didn't like him, because his mom has pointed out for a long time how much alike we are, and the more I've gotten to know him the last couple years, she's right. She has a running joke that due to some sci-fi time warp kinda thing, he's somehow actually my son. Other than the fact he looks so much like his dad, she's not wrong. The resemblances between he and I are many and noticeable.
But it's probably asking the impossible to enter marriage at my age for the first time, with a blended family, and encounter zero snafus. Mine is that the kid constantly knocks the A/C down and leaves lights on everywhere when he's here. I don't by any means keep it hot around here, but there's no need for it to be freezing. And my wife tasked me with the family budget (which I happily took it, I'm a nerd that way, and I'm good at it) and one item on the to-do list is get her big electric bill down. These are both actions I don't identify with because A) my folks drilled into me from an early age turning off lights I'm not using and that I can adjust the thermostat when I pay the bills, B) I'm anal and I was born this way, or C) both A and B. Frankly, at the moment, we need to scrape all the pennies together we can to keep these boys in college. I tend to project my thinking onto other people, and particularly a kid who otherwise is shockingly like me. It almost never crossed my mind to touch the A/C growing up, because my mom and dad would've said exactly what I just said, I'm welcome to put the temp where I want it when I live in my own place. Otherwise, they're keeping it where they want it either for comfort or for the bill's sake.
It's not enough of a thing for me to make a thing out of it, and my wife would like to avoid there being any "things" between us, so I'm careful to not to fight any battles that don't really need fighting. And I understand that....I had a stepdad in my later growing up years and I know my mom didn't want "things" between me and him either. I also never touched the dude's thermostat while I lived with them.
So I just go along behind him throughout the day and cut it up a couple degrees from where he cuts it down. It either doesn't cross his mind that the interface keeps mysteriously adjusting on him all day, or else he knows what's going on and thinks it's his prerogative to put it where he wants it. And I cut off the lights in his room and the spare room that is kind of his rec room every time he leaves the house, because cutting off lights is not a habit he has. A lot of times I cut off the TV and gaming systems in the rec room too, and I'm pretty sure he and his friend leave them on all night when they get tired and go to bed.
It irks me a little bit.
But like I said, there's a thousand worse ways he could be causing us grief, and while I would personally try to drill different habits into my own son so he doesn't waste money one day, it's a pretty small nit to pick in the grand scheme. My wife raised good kids.
