I hadn't thought of this before but this just came to mind: why did Suho stop Bumseok from attacking the bully with the mic but he didn't stop Sieun from beating Yeong Bin with the book?

I get that Suho's whole philosophy about fighting is "don't cross the line" but what made those situations different?

I don't know if I would call them theories but I have some possible suggestions. 1. Suho actually witnessed the mounting bullying & teasing that Si Eun experienced so he felt the payback was fair and justified 2. Suho could tell Bumseok wanted to blungeon the bully (potenially killing  or seriously injuring him) and Suho didn't want to be a party to that especially since it had been Suho's idea to confront them in the first place. 3. Si Eun handled his bully/bullies by himself yet Bum Seok was reliant on Suho's presence which made Suho feel responsible for the situation.

Does anyone have any thoughts on this?