Who is The Traveler from My Soul to Keep and what is their importance?

The Traveler performs the Ritual of the Living Blood on Khaldun, hoping that Khaldun will perform the ritual on him. Instead of complying, however, Khaldun lets the traveler die. It was the traveler's idea for the group to drain the blood from Christ's veins after his crucifixion and use the blood to give themselves immortality.