To help me answer your question, please clarify:
* Which character are you referring to? There are many characters in *Supernatural* who serve as vessels for demons, angels, and other beings.
* For example, are you asking about:
* Sam Winchester who was possessed by Lucifer for much of the series?
* Dean Winchester who was possessed by Azazel in the pilot episode?
* Mary Winchester who was possessed by the demon Meg?
* John Winchester who was possessed by a demon in Season 5?
* What are you interested in knowing?
* Did you want to know how they were freed from the vessel?
* Did you want to know what happened to them after the possession?
* Are you looking for specific details about a particular incident with the vessel?
Once you provide more information, I can give you a more specific and helpful answer!