Molly is one of the students at the school and helps the Protagonist with Jane's personal classes.
She works in the item store and, if enslaved, can give you free items. Abusing this causes her to get fired and the free items cease to exist.
She's a very nervous person, who is attending Jane's classes as an assistant to get enough credit to pass the school year.
Unlike most others, Molly lacks any form of damaging magic initially. Instead, she relies heavily on Support magic, healing especially. She's the first - and currently only - character to have a spell that lets her heal the entire team at once.
Succubus Molly
Giving Molly enough Love Potions causes her to turn into a Succubus, leading to an alternate plotline in which you have to feed her or she'll go crazy and escape.