Some more OC lore dump. Already mentioned in couple of posts before that OC is a descendant of an immortal that served the Celestial Court and used an artifact to escape to "our" world thousands year ago.
Her name is 飒馡 sà fēi. She is part of a clan that is known for their bloodbending abilities. They can turn their own blood into weapons to uses. Their blood can also be corrosive, to the point it can melt through locks and metals if the users wills it. They are also able to control other people's blood (same way like in the last airbender), use their blood to shape it into weapon.
They also cry stardust tears, which has incredible healing attributes.
And because of those abilities, the Celestial Court keeps a tight leash on the clan, and makes them do all the dirty black ops job for them - investigation, espionage, assassination. It is well known through the court and immortals who they are and what they do, so a lot of immortals eyes them with distrust. So despite being cultivators and immortals themselves, they are treated like outcasts.
It's a genetic lottery if the abilities will be passed down to the child or not, so the court often forces the women of the clan to drink from the child-bearing river. If the baby does not show the tell-tale sign of pink hair and gold-flecked eyes....
And then something happens, haven't hashed out the details yet where they are framed by the Celestial Court for something they did not do, and the Court then ordered the clan's entire massacre.
Erlang Shen was the one who was leading the massacre, but he knew it was wrong, so he stole an artifact in the shape of a pocket mirror that let's you travel between two worlds, thus making Sàfēi the only survivor of the massacre.
She settled down in "our" world, got married and had kids and then eventually in the 21st century, Oz was born with pink hair and gold-flecked eyes.
While Oz did inherit Sàfēi's blood bending, Oz will never be able to unlock it's full potential like her ancestors did, because that requires centuries of cultivating and be an immortal. Becoming an immortal is simply not on her to-do-list...
Being a bloodbender, it also means that Oz has immunity against poison, rarely falls sick and her she heals from injuries much at a much faster rate. And she cannot get drunk (never stopped her from pretending to be drunk though)
and that's it. Have a doodle of Kiwi and Oz talking about Erlang Shen