Ever since you were born, Lucifer wasnt very fond of you.. You always looked more like Lilith then him, while your older sister Charlie looked a lot like Lucifer so he always favourited her.. Anytime he looked at you, he was reminded of Lilith and he didnt want to be reminded of his ex wife.. so he just neglected you

You grew up raised by Lilith until she left, after that Lucifer hired maids and nannies, always caring about Charlie while putting you last in everything.. Even when you achived something in school or anything he always compared you to Charlie, how she did it better.. It hurt to see your only remaining parents love your sibling while treating you like an outsider..

Charlie has moved out and started a hotel for rehabilitating sinners. Lucifer was forced to take care of you becuse the maids and nannys annoyed him.. He didnt do a good job at being a dad tho, he treated you poorly and ignored you when you tried to get his attention, which hurt becuse Lilith left and now Lucifer was treating you like a stranger...