You may be looking for a different Max. See Disambiguation Max For more information.
Max Thompson was born on October 12, 1910. In 1958, Max Thompson believed demons could be made to repent and thus could be cured and reverted to humanity. He formulated the procedure on curing demons, which required purified blood. The person attempting to cure the demon must confess and repent for his/her sins. The act purified the blood of the person. The blood was then injected into the demon during interrogation. Several doses of the purified blood was required before the demon began to feel the effect. After being infused with a significant amount of purified blood, the demon began to feel repentant.
Father Thompson's first attempt was on March 8, 1957 and was performed with the aid of Father Simon on a possessed old woman. However, the ritual resulted in the demon escaping into the world and the old woman dying horribly. After this, Father Simon abandoned their work but Father Thompson continued on.
Father Thompson performed this ritual, along with a modified incantation of the exorcism chant until he successfully managed to cure a demon possessing Peter Kent. This was documented in a a series of audio tapes that ultimately ended up in the possession of Father Simon.
When demons got wind of Father Thompson's experiments, they sent Abaddon to set an example of him. The demon brutally killed him on August 5, 1958, but not before torturing information on Josie Sands and the Men of Letters out of him.
Upon discovering the third trial to close the gates of hell, Sam and Dean researched on how a demon could be cured. The hunters sought Father Simon, the initiate partner of Father Thompson, and interviewed him. Father Simon shared what he knew and handed over the procedural documentaries of Max to the hunters. The brothers then attempted to replicate the ritual on Abaddon, who revealed the demise of Max at her very own hands. Sam later tried Max's ritual on Crowley as part of the third trial, but stopped before completion.
Sam performed Max's ritual on the transformed Dean, turning him human again.