Board Thread:Speculation House/@comment-1292715-20181223044830/@comment-26397825-20190425033310

Theory: Maybe Cinder isn't the first artificial Maiden Salem made, and Summer was killed by the previous False Maiden+friends (mortally wounded), but not before Summer got a blast of Silver Eyes off on her.

It explains how Salem knows for certain that Silver Eyes affect Cinder negatively beyond a simple guess of "Silver Eyes + Grimm = Bad". It may have something to do with her wanting to use Ruby as a failsafe in case of backstabbing from people like Cinder, or she may want to see what happens to a Silver Eyes Warrior if they get implanted with a Grimm Bug and then use their eyes.

She might even want the Grimm parts of her gone so she can be more rational or something (though this is a potato theory). Or hell, maybe she knows the SEW are descended from an Ozcarnation and Ruby is the last one 'alive' (that she knows of) and wants to make Ozma suffer for moving on with his life and having more kids after their fight killed their daughters.