Do you also have an OC that's possessed by some kind of entity? If so, how did they get possessed in the first place and what's their relationship with their parasite?
Oren Escudero (slide 1) is a sweet boy who can do no harm.
Unfortunately, he's possessed by Kizakia (slide 2: Kizakia in Oren's body), the ghost of a 12 year old child that wants to do harm. As in he wants to exterminate all of humanity.
Oren was actually never meant to be possessed. While Oren's mom was pregnant, she was actually supposed to have twins. Kizakia possessed one of them, sensing their enormous power, the ideal host. Unfortunately, Oren ended up absorbing his sibling in the womb (a common occurrence when pregnant with twins, it's called vanishing twin syndrome). So that means Kizakia was suppressed in Oren's body until he turned 16, when he started emerging.
Oren initially was afraid and hated Kizakia, but, after learning how much he suffered, Oren started to feel bad for him, even downright refusing to be exorcised, even if Kizakia previously almost killed his friends multiple times. In my oc universe, the human race was saved from genocide... because Oren is really good with kids