whoa M16's eye is still intact here..

Flashback, I presume?

prob.. I mean UMP45 gone rouge/AWOL right after the death of UMP40, she prob got caught by M16 and then take a deal and become the leader of Squad 404

It's a flashback. Deep dive's flashback ended with 45 getting in contact with someone, I always presume it's M16.

Current event is said to explain behind the Butterfly Incident, such as this.