But that only happened cause vaatu went like in korra's mouth and pulled raava out and pomegranate, right? lol
Spoiler
Well, no. He pulled Rava out, but he killed her, it's not like he ate her or absorbed her or anything, he hit her until she died and then she faded away. When Korra was in the tree of time, she heard a flashback of Rava explaining to Wan that one can't exist without the other, they are completely bonded. Hence why Rava "respawned" inside of Vaatu.