Misty is the Lacerta saint in the XX Century.
Misty was an Athena adorer, but, below her, he he said the most beautiful thing in the world; with his defensive powers, Misty never allows something to hit him, for don't hurt his beautiful body. So, according him, how much stronger the person, less he will be hurt.
In the Episode G, Misty fought against Athena enemies, because Saga manipulate the saints to serve him as a leader of the Earth, ergo, all the Athena enemies and Earth enemies was Saga enemies; so, during the fight against Athena enemies, the servants of Saga and the servants of Saori Kido, fought together
Misty was sent to kill Seiya in the anime and the manga, because he disrespect the Sanctuary law. But, in the manga, Misty attacks the Mount Fuji and kill Ikki (another sinner) and Babel, Asterion, Mousses and Marin was sent with him; but Mu teleports the black saints and Seiya, Shiryu, Hyoga and Shun and Marin guides the three conrades to kill the wrong victim; Babel kill the Black Cygnus, Asterion kill Black Andromeda and Mousses with Black Draco, and these black saints was confused with Hyoga, Shun and Shiryu; Marin simulates kill Seiya, and the 4 corpses are buried in the beach; but Misty ask to Marin, Mousses, Babel and Asterion. Misty waits Marin leave the place, and pulls Seiya (Misty only perceived something wrong with Seiya and don') to out of his grave, and fights against Seiya again, swearing punish Marin to her betrayal.
In the anime, Misty only goes kill Seiya with Marin, and Asterion, Mousses, appears later apart of Misty and Marin.
Seiya discovery the weakness of Misty barrier: in his backwards, Misty can't make his barrier, so, Seiya attacks Misty from behind with his Pegasus Rolling Crush, and kill him under the sea. In the manga, Seiya leaves a card with Pegasus symbol on the body of Misty, and Hyoga repeats the action of Seiya with Babel.