Marcus

Marcus was a very prominent person who lived in ancient Michina and was the mastermind behind the whole plot to betray Arceus. Marcus was a sly and evil person and many people followed his orders. Marcus believed that the people of Michina should keep the Jewel of Life otherwise the land would return to its desolation again.

Marcus had no intention of returning the Jewel back to Arceus when it returned. Marcus go Bronzong to use Hypnosis on Damos and made it look like he betrayed Arceus. Arceus got mad and Damos and Marcus fell to their death.

When Sheena arrived with Ash and his friends from the future, Marcus put Ash and his friends in prison with Damos. He pretended to be the good guy and questioned Sheena about the future. This time when Arceus appeared to get the Jewel back, Marcus gave Sheena the staff that held the Jewel. When she opened it in front of Arceus it was gone.

Since Marcus knew about the future, he was ready for Arceus and he got all the Pokemon to use Ice Beam on it while they dropped Silver Water on it. Ash and his friends were able to stop Marcus and this time only Marcus fell to his death.