Val

Valentine, or just Val as he preferes to be called, is a Kihirin, a  species I've created some years ago, however he is not a regular  Kihirin.  

Hundreds of years ago there was a king in the Dark Kingdom who created a  spell attempting to make his soldiers stronger, however that spell went  terribly wrong and made the soldiers live in agonizing pain until the  end of their lives.  That curse passed from generation to generation until it reached Val's  mother who married a Kihirin and Val inherited the curse. 

"So what does this curse makes?" you ask.  Right away the person gets irregular marks on the body when the curse is  "activated", usually only on one side of the body and in the color of  their eyes (in Val's case: orange and in his left side).  The curse gives the ability to possess other people and the cursed ones  heal themselves very quickly from any wound, so it is only possible to  kill them with poisons. However, whenever the curse's powers are being used,  the cursed one suffers an immensely agonizing pain.