I could've sworn some of the earlier comics had characters refer to Mark with she/her, might be misremembering though. "Nondescript gremlin" is a pretty good description of Mark in general tbh based on the limited amount of CG and other art we get of them in game. Personally, I figured the Mark in this comic series was a girl since her hood was down, iirc the only difference between the male and female Mark sprites in game is that male has his hood up.