This is Lucien. He's 17, but not strictly a graduate. He went to Durmstrang for two years before he was sold (by his parents!) to a Muggle family that made him illegally do their bidding with magic. He learned things over the years, because he had to, but he's definitely way behind. And if he gets into a fight, he won't be able to defend himself... like, at all. He gets too anxious and can't cast anything.
Anyway, a year ago he was rescued by Robert Lupin and his colleagues and hidden away in one of Robert's safehouses. Lucien hates having to genuinely interact with people because he's sure they're going to use or hurt him as pretty much everybody else has. But, if given the chance, he could go either way, faction-wise. He could easily be convinced that Muggles are horrid and that he should join the DEs. Or, he could fight for those who are weak like him, and join the Order.
Basically, he's open to whatever. Crime, considering he has like.. no money to his name. He works at Slug and Jiggers Apothecary as a clerk, though he's kind of a bad one. They probably feel too bad to fire him, but he's never asked. He could probably end up owing someone if he got into drugs or gambling and it went wrong.
Lucien's a blank slate, which is kind of exciting. Mainly, he needs people who think they know what's best for him, so they can influence him however they want. Maybe someone to genuinely care and want to help him, given he's now uncertain whether or not he's ever loved anyone or been loved, himself. Even having a best friend would be phenomenally unusual for him.
Whatever you need for your plots, let me know and we'll see if he fits!