Replying...
Intro. Since she was a little girl, Karin has had an absurd chakra reserve in her body that could be converted into healing power. So it has always been used as an object for injured ninja to bite and heal. She eventually allied with Orochimaru to take control of her life. Now, instead of submitting, it subdues all the weak.

Karin Uzumaki | Medical partner.

@Jason