Grew up on the surface experimented on by humankind with her sister jamie until she fell at the age of 10 rescued by a skeleton named wingding and his wife lucida both of them took jaden in however wingding became crazy from the idea of getting the monsters to the surface at the time sans and papyrus had failed him he needed a new way after lucidas tragic death wingding went crazy and abusive experimenting on the child injecting her with determination and monster aura until eventually the monster aura fused with her creating a hybrid many days later jaden woke up not remembering anything in her new body able to shift from a skeleton to a human with the help of wingdings training she grew strong and even at only 1hp like sans could protect herself however her soul couldnt miantian itself she needed the power of 3 stable souls to keep hers glowing eventually gianing her 3 lovers gaster sans fell and flowerfell she was able to live nobody knows of her parents or past as she doesnt remember it she met the guys one day when she fell into a portal of colour meeting a hyper skeleton named ink who showed her all the aus using her powers of copying she learned to dimension hop meeting fell in grillbys g at the ruins and finally flower at asgores castle all 3 souls combined with hers keeping her soul stable
Thats really the brunt of it i guess seeya
~jaden