I always imagine these two as recurring antagonists in a video game; they keep showing up and give you snippets of dialogue and situations that make you feel like they have their own story going on, but it's outside of the main story so you mostly just get those glimpses.
I also imagine that Mills would eventually start to think of the player protagonist as a friend, because they keep beating the tar out of each other without anyone dying.
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Sakke
Incriminating teethmarks is so a tag