Remus has this theory that his friends, the only beacon of hope and light in what is otherwise a total wreck of a life, only hang about him for the novelty. It's a sad theory, really, though not one that is all that difficult to believe. He really has no reason to be sore about it, though. What right does he have to ask for friends who actually appreciate him? As long as they don't out him to the school he owes them everything.
If that means he has to let them get away with a prank or three every here and there or write a transfiguration essay for someone every third week, it's a small price to pay for secrecy and the continued pretense of camaraderie.
And if Sirius gets sexual favors sometimes… well, it's not like he isn't enjoying himself, too.
Sometimes he finds it easier to think about the future in terms of everyone just stopping pretending to like him. He imagines James growing out of him, as Remus knows very well that he will. Telling Remus that it was a fun run while it lasted, but that he has domestic grown-up things to worry about now. It's almost a source of comfort. Then at least it will be over and done with instead of leaving him with that terrible nagging hope that maybe it's all in my head filling up spaces that he needs to use to remember how to breathe properly.
And he can almost see Peter just ignoring him one day. He'll see him walking by, Remus living out of a cardboard box on some sidewalk in Nocturn Alley (because that's where he just knows he's going to end up just before things go really badly) asking for money so he can get a cup of tea and some chips to tide him over. He'll call out, "Peter! Could you spare a knut for an old mate?" and there won't be any answer. Because despite how well he keeps up with the Marauders' Mischief right now, Peter will end up doing things properly, and dark creatures are anything but proper.
The future he envisions with Sirius hurts the most. He just... disappears. There really isn't any other sufficient word for it. They have a romp one night, and then he's gone in the morning. And never shows up again. No goodbye, no explanation, no fight or hint as to where he's gone or why. Just, he's suddenly gone, and Remus can't even move on with his life properly since he doesn't know anything and can't properly disengage his mind from someone with whom he has spent nearly a decade. Not that he's so obsessed with his own self-import that he thinks he deserves any sort of closure, just that it would be nice.
And then there are the days that Remus feels minimally miserable and can actually manage to convince himself that maybe he is just paranoid. That maybe his friends really do keep him around for his company and not just what they can get from him. It's during these periods of time that he can put a stop to some of the mischief and tell James to do his own damned potion work. Even start to convince himself that maybe Sirius could actually need him specifically instead of just anyone with low enough self-esteem to give in every time he so much as quirks an eyebrow.
He'll start hoping again, that dangerous hope, that maybe there can be a future for him. That maybe he can live as a muggle, selling books from some old thrift shop that smells like age, seeing everyone on nights and weekends. That maybe everything doesn't have to change when their time at Hogwarts is over.
Sometimes these periods of time even last as long as a week.
But then he'll see Peter and Sirius talking when they think he isn't paying attention, or the dorm will get quiet when he wanders in, or he'll catch some snippet of conversation in which his name pops up and he'll snap out of his little fantasies of actually being a real boy.
And end up back in the world where he's just a charity case with a beast stuck in his skin. In which he's used for the sense of adventure that his condition brings to second parties; in which his fine, scholarly mind is taken advantage of and demanded of to compensate for the laziness of others; in which his body is really just up for grabs whenever his best mate wants it.
He'll pray to any deity listening and wish upon every star that he can actually just be paranoid. He'll let himself fancy himself a person worthy of the affection and acceptance he imagines during those brief, deluded moments that seem so real that they almost could be. And then he can't help but hate himself just that little bit more for wanting more than he has.
It's already so much more than he could have ever hoped for.
And so fantastically much more than he deserves.