so i see them as ~6 years apart but lets say just they're in the same year at hogwarts.

barty and sybill are both outcasts but for different reasons. barty outcasted himself - made himself seem like such an unlikeable know-it-all that none of his classmates went near him anymore. sybill, however, was made an outcast from the day she was born, someone everyone avoided because she was too weird.

naturally, they ended up next to each other, because nobody else would sit with them or there weren't any spaces left. sybill sees this as an opportunity to make a friend, or at least form an alliance, whereas barty isn't really interested. that is until he remembers sybill's seer abilities.

suddenly, he's all over her. he won't stop asking her questions and prodding her about her abilities and trying to find out as much as humanly possible. it's mildly annoying to sybill but she also doesn't mind it much because finally someone is interested in talking to her. i can see them becoming friends through this as barty realises that sybill is actually more than her gift and can also be an interesting person, someone who makes him think about the world through a different lens.