Damos once witnessed Arceus sacrificing its life to save the world from meteors. Arceus sustained heavy damage doing this, and lost possession of its Plates. Damos returned them to Arceus, and as gratitude for saving its life, Arceus granted him the Jewel of Life, made of five of them, to revitalize Michina Town, at that time a wasteland.
Though Arceus made Damos promise to return the Jewel of Life at the time of the next solar eclipse, Marcus was fearful that Michina Town would revert to its lifeless state if this was done, and together the two betrayed Arceus, with Damos under the control of Marcus’s Bronzong’s Hypnosis.
Ash, Dawn, Brock and Sheena travel back in time with the help of Dialga to prevent Arceus’s betrayal. It was revealed Marcus used to be Damos’s underling but overthrew the latter and put him in prison. There he finds out from Ash and co. that he would betray Arceus in the near future and that Marcus is behind everything. Thanks to the help of his friend, the Spiky-eared Pichu, he managed to break free. He saved Sheena from certain doom and managed to convince her that he isn’t a betrayer like the legend makes him out to be. Together they stop all of the Pokémon from attacking Arceus by connecting with them. Damos manages to break through Arceus’s anger and connect with it thereby calming it down. He then later bids farewell to the “future children” and makes a stone engraving with them on it for them to see when they get back to the future.