@LadyTaleOr his powers can be fear itself. In some way wherein he can instill a specific kind of phobia towards a targeted host. Once connected, your character can toy with the host's perception, making him witness a number of hallucinations manifesting from the fear the host's newly attained phobia brings.
His secondary power is that he is able to exit his corporeal state and become an apparition-like being capable of passing through walls like a ghost. This doesn't mean he's invincible, once his body receives physical harm, he will be forced to return to his normal form immediately.
Idk, it's a bit unclear for me how this will work out but this can be a thing.
@FantasyChic It's alright. Take your time, nothing's on the rush here. ^^