Erin was kidnapping/coercing children to join her tower because long ago her children were stolen by the hands of time. Though she was loving towards them and gave them all the resources they needed their talent was poor just like her late husband, and thus their lifespan was only a few centuries at most compared to her previous and future millions. She created a spell when she was young of eternal youth and accidentally cursed herself with it.
At the time she was overjoyed and hailed as a once in a trillion years genius, she soon realized it was a painful curse though as all her loved ones, friends, and everyone else she knew died leaving her behind on her infinite path.
[A/N she tried to 'curse' or 'bless' her loved ones, but the spell only added a decade or two at best. The reason why is that they need to supply the mana or Qi for it to work, or else it will fail using their mana/Qi essential marks them in the spell causing eternal youth, but you need lots of mana/Qi to be able to. Which is why Erin seeks only highly talented individuals to be her 'children']
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Lily had her family, but she felt excluded because everyone else got adopted or left early after getting a job. She however stayed to take over the nursery as the new caretaker after her Nana(Diane) left to pursue her dream to travel after spending 30 years there.
Here, in Erin's tower, she felt loved and included, happy, even though she knew she was kidnapped she felt true happiness...
even her soul felt this way.
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"Lily darling, come to my room please."
"Yes, Mama!"
As Lily ran upstairs she suddenly fainted.