Michalis kills his father, the previous King of Medon, as he feels that he was a weak ruler. He is eager to prove that Medon is the strongest nation in Akaneia and have the right to conquer the land, thus he agreed to ally with the Doluna Empire. Seeing possible conflict with his sister Minerva, he lies to his youngest sister Maria and has her imprisoned to keep Minerva in line. He feels remorse for this, however, despite the fact that he feels no remorse about killing his father. He originally planned to fight Doluna once Medon was the most powerful nation but he lost sight of the goal the longer he worked with them. If the player recruits Matthis using Lena and has Matthis talk to Marth, Matthis originally believes Marth will kill him (Matthis, that is) because, as Matthis then tells Marth, Michalis "puts the most scared-looking soldiers on the front line for a reason" and kills those who defy him. He is, however, tolerant with Gotoh, who keeps warning him that he is walking to the path of destruction. He finally faces his sister Minerva in battle and where he was badly wounded and was presumed to have died.
In Monshō no Nazo, it is revealed that after this, his sister Maria tended to him with utmost care and it healed his soul. When he heard Maria had vanished, he worked alone to try to search for her, also rescuing Minerva and sending her to join Marth. In the end, he managed to steal the Starlight spell from Gharnef, but was badly wounded. He managed to give the spell book to Marth before finally succumbing to his wounds.
However, he can survive in Fire Emblem: Shin Monshō no Nazo ~Hikari to Kage no Eiyū~ by having Minerva wait one turn on the village he is on, followed by having Marth visit it. After the war he resumes his position as King of Medon, only to later leave and become the king of a kingdom on a different continent.
Role in Super Smash Sisters
Michalis is an NPC helper in Super Smash Sisters. Unlike in Shadow Dragon, Michalis is reformed like he was in Monsho no Nazo. He uses a Silver Lance for main combat and can use his Javelin as a projectile to hit far enemies. When paried with either Minerva or Maria, they can do a team final smash.