Jason Blood is a recurring character in the TV show Future Constantine , he is played by Keanu Reeves
Jason was a knight who fought against a witch named Morgana, to help in the fight the wizard Merlin summoned the demon Etrigan. The battle was won but Etrigan was still thirsty for blood because of this Merlin fused Jason and Etrigan together. Over the years Jason's good natured personality would rub off on Etrigan turning him chaotic-good.
Blood's first episode in Future Constantine had him and Etrigan ripped apart by Klarion the witch boy who wanted Etrigan to do his bidding. Throughout the series he would slowly develop in to a friend and the love interest of Katherine.