barty's just been sorted into slytherin and manages to slide himself between regulus and evan when he manages to find a place at the slytherin table so he shoves between them and raises his eyebrows at the older student opposite him who's frowning at him as if to ask if there's a problem. it's well known in slytherin who barty's father is so the student looks away and barty smirks.
the three of them get to talking and that year, it ends up with barty being given all of evan and regulus' notes from their first year so he absolutely excels in all of his classes (even transfiguration, which has never been his strong point). his teachers aren't completely sure what to do with him so he just sits in a corner in his lessons, practising what evan and regulus have been doing in their classes.
he begs and pleads with his father to pull some strings, strings get pulled and barty gets pulled aside at the end of the year by the second year teachers because they've caught onto him practising spells he shouldn't ought to know just yet. his mother keeps him updated through letters and floo calls before the summer: his parents have been talking to his head of house, his class teachers and they know how close he is with evan and reg and that he'd prefer to be in their classes next year rather than with the slytherins that he's barely spoken to in his year.
during the summer, there are strict promises made from his end that he'll keep up with the workload if he's moved up a year, but old Slughorn seems fine with the move and what's Professor Dumbledore going to do but disagree? barty's had perfect grades through first year and his teachers seem to accept that he'll be able to keep up. so come september, he's back on the train clutching a letter from Dumbledore and Slughorn, trunk full of third year items. he finds regulus and evan who at some point became friends with pandora lovegood and dorcas meadowes and they're all sat together in what pandora likes to lovingly call their usual carriage.
he waves the letter at them in way of greeting as he unshrinks his trunk from his trouser pocket and heaves it onto the luggage rack. "joining you in the third year dorm this year lads, whadda ya think of that?" evan grins at him, eye glinting in the sunlight and regulus lets out a whoop. "you'll have to do your own work this year though, no more using my notes or my mother will have my head and you know what she's like when she's angry." barty knows all too well the famous walburga black howlers that come screeching their way into the great hall every time she's upset with sirius. he winces in sympathy and jostles regulus as he sits down between the two boys, unknowingly matching the way they'd first sat the day he'd been sorted.
it's just so easy for him to fit into their classes that year, finally working at a pace that he feels a little challenged by and if he needs a little extra help sometimes, then he knows evan and reg can always give him a tip or two and none of their teachers will be any wiser for it.