So I read the novel version n kinda understand what happen. It's chap 19 in the novel. Bai Chunian wants to check Rimbaud's hole (cuz he care how is he treated with another alpha in observation box). But Rimbaud don't wanna let him see so he push BCN down. But, BCN release strong a oppressive pheromones to stimulate Rimbaud’s glands and reverse the position. BCN lift the fin under Rimbaud's belly (there is a omega's hole). BCN see the injury at Rimbaud's hole, but Rimbaud cover it with his hand cuz he shy (he's blushing!). BCN lose control and become angry when see the hole is in that state (thinks that alpha aggresively faq him) so he release his oppressive pheromones n grab Rimbaud's hair. He even bite him and say that he should be the one who do it (faq him). Feeling insulted, Rimbaud shook off Bai Chunian’s hand and released a large amount of oppressive pheromones in opposition. He even make BCN health bar reduce. After that, Rimaud left BCN, while BCN clear his head. After that, he go upstairs n find out that Rimbaud's is crying.