Doomguy:

As long as she doesn't do anything demon-like, Charlie will be okay.
Then again, Doomguy has been fighting demons for so long, he can smell their blood through his mask almost as if he has demon vision.

Best bet for her to survive?
Act natural and just sweep on the corner without talking and or interacting with Doomguy.
He hates talking and interacting with anything that lives and is either a demon.

Leaving him alone is the best means of survival.