Lamia is madly infatuated with Dantalion, going as far as to call herself his fiancee. Dantalion does not return these feelings.
Astaroth is Lamia's mother. Lamia is loyal to Astaroth and is her assistant and a member of her Household. She has a high opinion of her mother, and thinks her the most suitable to be the Substitute King.
Beelzebub is Lamia's father. Like Astaroth, she does not like him (and usually holds a fly swatter when he's close), though the reason is unknown.
Lamia is jealous of William after seeing Dantalion seemingly "kiss" William. (In actuality, Dantalion was trying to wake William up.) She is hostile to William the first two times she meets him, though William does not know why. Their third meeting is much more civil, possibly because Lamia has realized William is not a threat.