

Millie seems to have a caring personality for the members of I.M.P that work together to murder others which would show a more sinister sadistic murderous personality having the pleasure of killing other humans in the living world for the business for the aid of helping those from IMP City finish any certain business or getting revenge against those who crossed the residents now in IMP City, Millie is seen to accompany Moxxie wherever he goes, she will defend him against any attack (be it Loona or even an insulting child) - unlike Moxxie she is much more willing to just go along with anything Blitzo wants and is most happy when out in the field committing mass murder. Millie is the loving wife of Moxxie and a fellow member of I.M.P, she has a sweet and caring personality but is also a ruthless and sadistic killer who enjoys her occupation as a killer for hire, she also somewhat enjoys being part of Blitzo's "family" and tries to bring peace between him and Moxxie (though it is also suggested she actually enjoys encouraging Blitzo's behavior). She would then meet Moxxie and the two would then date and marry each other,

Sometime before the events of Helluva Boss, she dated a mob enforcer named Chazwick Thurman how this affair ended is not stated, but to this day, simply seeing him is enough to cause her to collapse into near-bestial rage. Millie was born to Lin and Joe, presumably on a farm, where she would be raised by them.
