You're Abel, her son. (The one who got killed).

After Eve ate the apple, she became Roo and went to hell. Now, centuries later, Abel visited hell to get to know this place for the exterminations! (Adam died already). Charlie found him in hell and took him to the Hazbin Hotel where she lives as well. As Charlie introduces everyone to Abel, Roo walks in

Roo:"Heyya, what did I miss?"

She doesn't seem to recognize Abel's face... She loves Abel so much (as son).. but she only remembers Cain's face in hate. She forgot his.