It is very obvious that Lethe & Mnemosyne have opposite personalities. I like to think of the phrase "two sides of the same coin" (see more on that with their relationship with each other). Probably also because one lacks what the other has. Here I will describe their personalities.


Lethe is the dominant of the two. You can probably see this in her bold personality but also in the bold colors Takeuchi gave to her. She also comes off as passionate, aggressive, overprotective and harsh. Unlike Mnemosyne, she just sees the world as it is: harsh, unfair and full of death. In a way you could say she seems pessimistic about life. She is first to attack Eternal Sailor Moon when she arrives and comes off as uncaring when she just kills Luna, Artemis and Diana without a second thought. She sees that the world is the way it is because of Sailor Moon and her Silver Crystal. It is not until Mnemosyne appears and tells Lethe to stop that we start to see a softer side of Lethe: The overprotective and passionate side. She is passionate towards protecting Mnemosyne but perhaps overprotective because of the war. When Lethe wants to kill Sailor Moon she tells Mnemosyne to just close her eyes. Lethe dosen't want Mnemosyne to see any more violence and appears to bloody her own hands so she dosen't have to.


Mnemosyne is the submissive of the two. She has toned down colors and often wears a worried or solemn expression. Despite the war, Mnemosyne still seems to have hope and think things can get better, much to the opposite of Lethe. In a way, it seems that Mnemosyne does not really blame Sailor Moon for all the violence around her. Mnemosyne appears fragile, trusting, gentle and maybe a little naive. She also has great influence over Lethe and her actions. She knows how far Lethe would go for them and tries to keep her from committing acts of violence. Mnemosyne helps Sailor Moon and her allies but also convinces Lethe to let them pass, to let Galaxia dirty her hands by killing them. This is a sign of her passive nature, not wanting to Lethe to dirty her hands for her. It would also appear she is quite dependent, for she is always clinging to Lethe's side.


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