Devi's dad is an unseen character from I Feel Sick volume 1, he announces Devi that her friend has arrived, and then gets over dramatic when he realizes they are going to have a date, he starts screaming that shes only 16 and is too young to date, and then tries to stab himself with a fork, though he is an unseen character, there is in the background of a panel, a photo in the wall of Devi and a man, quite surely her dad.
Devi's mother is never mentioned, and before or after that scene neither does her father. A fun fact about him is that he calls "Mija" to Devi D., this is a contraption of "Mi Hija" spanish for "My Daughter", used often in Mexico, this is more than likely a reference to Jhonen Vasquez's roots.