A Key to another Realm (An Mlb and Owl House Crossover)

Nathalie Sancoeur, Currently 14, has been living with an unfortunate curse that can turn her into an actual beast. The Only way she's been able to Keep the curse from taking over her and turning her into a Real Monster is by drinking a Special Elixer that she's mysteriously been getting. Though she doesn't know how she's been getting them or possibly 'Who' has been getting them to her room every couple of days, she's very thankful for them. And One day, along with the elixirs, she received a special type of stone with a note, stating that it would help her know when the curse is at its Surface

(This will be kinda before Luz Came like in the show, so Eda, for a while, won't be too fond of hugs. And also, in this, I'll say Luz is actually a Witch from the Demon realm. And same for Camila)
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One Night, After an unfortunate yelling Match and then an unfortunate, harsh beating as a punishment from the woman who Nathalie thought was her mother, for Protecting her Little sister, Caline, who's currently only 4 years old, soon turning 5, Nathalie finally decided that enough was enough and that she had to finally escape that house, With Caline, On That same night. So As it's becoming dark outside, Nathalie quickly packs a big bag with a few of there things, some clothes and some food and money to last a bit. And After Packing, She'll put the bag over her shoulder and carefully pick up Caline, who had barely fallen asleep, and sneak out finally, but as She gets out the front door, Nathalie's older "Sister" and "Mother" will end up catching Nathalie sneaking out, and so Nath will Immediately start running where soon she ends up in the forest and ends up finding a weird looking key, and in hopes that it'll somehow help her and Caline hide, she presses on the key and then appears a Portal Door to a realm called 'The Demon Realm'