Damos was a leader in Michina Town in the distant past. The land of Michina was threatened by a Meteor and Arceus saved the land by destroying the meteor. Damos saved Arceus and as thanks for saving its life, Arceus gave Damos the Jewel of Life to help rejuvenate the land. Damos promised to give the Jewel back to Arceus the next time there was a solar eclipse.
Damos loved the people and land of Michina and had even intention of returning the Jewel back to Arceus when it returned. Unfortunately, he was betrayed by Marcus who thought it was best to keep the Jewel. Arceus got mad and Damos and Marcus fell to their death.
When Ash and his friends arrived in the past the met Damos in the cell and realized that he wasn't the bad guy that history had made him look like. He has been controlled by Hypnosis. With the help of Ash and his friends, Damos was able to return the real Jewel of Life to Arceus and asked Arceus to forgive him. Arceus knew that in Damos' heart that he was a good man.