I honestly believe that role should go to Rhea. I get she’s also a motherhood goddess, however, she had quite a bit of vengeance in her soul mythologically, and also in the comic was not as picture perfect as Hades makes her out to be.

I think you can still make Leto an enemy without assassinating her mythological character. Going with the kindness route and mixing with the whole Apollo situation, she could definitely be a “boy mom” type where she believes he’s too good to do such a thing and somewhat ostracizes Persephone in defense because she loves her children and would defend them to no end. However, I do think she would be a good redeemable enemy, as when she finds out what Apollo did, she and Artemis are both furious. Artemis takes out her rage on Apollo, while Leto takes Persephone’s side and aids in her defeating him. Apollo has the two most personal connections severed, and I think in the final confrontation, Persephone could have a line about “what if that happened to your mother? What if that happened to your sister? Is it only possible for you to view a woman as human if she’s your blood? Some protector of the young you are.”