Responses
Yee, Aaron couldn't get all of it out 'cause Cain started to force his power out to keep Gyeong from waking up and dying I'm assuming. He started seizing there towards the end and judging by how freaked out Cain was when he noticed Gyeong's body fading out of their consciousness it was probably very likely that he would've died if Cain waited even a second longer.
He only got half the bullet out? Soooo, means the bullet is not entirely gone from Cain's body??