Revenants are a type of Undead that exist in the world of Pact. Revenants are individuals who’ve suffered grievous and fatal wounds, but they refuse to stay dead. Most only return to life long enough to accomplish a goal, such as a mother returning long enough to save their kidnapped child and bury the kidnapper, or a businessman returning to life a day or two in order to get his affairs in order to leave a legacy behind. Once they've accomplished this they normally cease to be.
However, when there is so much hatred driving the soul that it clings to the body and forces it to move they can become revenge-driven killing machines, described as serial killing zombies with a theme by Blake. Should they not be able to accomplish this goal, due to the death of the one who they sought revenge against, they might linger around and calm down.
Because Revenants are undead, they do not feel the elements. However, they do not suffer the same drawbacks as a Ghoul because they weren't unbalanced when they died, allowing them to retain their sense of sanity, although they are driven by rage that urged them rise from the dead.
Once they calm down they can be used for whatever ability and talents they had in life that carried over in death, such as Tallowman being able to use his wax in a variety of ways. However, they also have weaknesses based on this.