Roost was a very different sort of boy, who was more isolated than teased. He doesn’t mind being outwardly alone, it doesn’t bother him at all. He knows that in his heart he has his family with him and that his family is always worrying and thinking and caring about him in their hearts. Keep in mind that while Roost doesn’t remember much of it, he has enough memory of being an adult he’s able to process conflict better than a child would. He’s absolutely not afraid of bullies because he knows that he’s loved and important and that he can trounce them in a fight. The intrinsic above-ness that he has over any unkindness intimidates anyone who would think of teasing him for being different. The sort of things that hurt his tender feelings are in a different wheelhouse that tend to make the people who hurt him more apologetic and guilt ridden than smug.

The professors had to get over themselves for their own self-preservation. He would be discovered in the library in the morning surrounded by a pile of books and watching live streams from the space station. Or they’d find him at midnight in the chem lab testing out the chemistry lesson because the formulas seemed a little off. He hated English and was alright with history as long as he had access to lot of historical records that would drive other people up the wall. Merchant books and poor law records and military reports. He did well with numbers.

He had his English professors endured each other as a necessary evil. His final year he turned in papers that looked like esoteric found poetry. Source quote after source quote linked together with sort, to the point analysis. He always formatted correctly though. Exactly the right amount of words, exactly the right font, exactly the right spacing.

Added to that, as you said, Roost is extremely endearing. He loves holidays and loves giving little Christmas gifts that are cheap as anything but so charming and cheerful. A few kids would try to be smart from time to time and crumple up gifts or be petty and cruel. He would give so few bothers about it, telling them it was their gift, if they didn’t want nice things they didn’t have to have them it only happened a few times. As a result a lot of people who had been taught to detest kindness by their jerk parents made big deals about his cutesy presents and treasured them. It made this weird upside down sort of social circle for Roost where all the Draco Malfoy types would go just about giddy for construction paper Valentine’s cards and little bags of Christmas sweets.

He wasn’t popular, nor did he have a huge group of friends, but his willingness to share made the people around him feel like they were part of something lovely. Everyone loved working with him, even people who are too wound up to enjoy him in a social setting. He didn’t leave school with best friends forever, but there will be students that grow up into the sort of cold-hearted investment bankers people mistake for the devil, that will make serious effort to stay on his Christmas card list.