BakuDeku- Different but Yet Still The Same Kacchan

SO basically Quirks aren't a thing, and Bakugou never bullied Deku. But he was still really rough with everyone expect "his Deku". This caused him to get expelled from their middle school. As a punishment his parents sent him off to boarding schoool until their second year of high school. What will happen when "his Kacchan" gets back with a whole new look but still the same old Kacchan? and why did Katsuki's parents suddenly decide to send him back?