You know what's weird?

Scaramouche (Wanderer, Balladeer, what have you) has a teen boy model. But he's the prototype for Ei's puppet body, so you would think that he would be indentical to her like her next puppet is (Raiden).

Of course, there's some great trans!Scara hcs about this that I personally absolutely adore. But we see in flashbacks that even when Ei first abandoned him, he looked the same as he does now. Most theories that he altered his body posit that he did so after joining the Fatui, since in Inazuma he wouldn't have had the resources. But his body starts out small and rather androgynous, which implies that he was designed that way.

There's also the inconsistency in how Yae describes him. A 'prototype' (as in, a test version of the intended final product), but that wasn't Ei's original intention for Scara because it's said that she chose to pass him only over after seeing him cry. So she designed him as though he would be the next ruler of Inazuma, not as the test version that he ended up being.

Ei's intention after Makoto's death was to preserve her consciousness, protecting herself from natural erosion by sealing her mind away. This is why she needs a puppet; to carry out her will in Inazuma whilst she's meditating endlessly. It is her will so it is logical to make a puppet identical to herself, as a facet of Inazuma's 'eternity' if nothing else. Scara... Why make him? Why would her instinct be to make a puppet who looks like her and (moreso) like Makoto, clearly a relative, but not close to an exact copy.

I think it's because she was attempting to share her grief. Because Ei and Makoto shared archonhood, very few people are aware that there were two of them. Therefore, so long as Ei lived the public could never mourn Makoto. But if Ei disappeared and her son took over, then finally Makoto's loss would be felt by the entire nation. We know Ei felt guilty, but how much worse did she feel, as though she had stolen her sister's life completely unintentionally? So her plan: craft a child (a daughter, if we're sticking to trans!Scara), and 'pass on' herself. Scara would still be a puppet driven by her will , and Ei would still be alive in her personal meditative realm, but finally Inazuma would appreciate Makoto's sacrifice.

However... When she sees Scara crying in his sleep, she can't go through with it. She's reminded of her pain and has the protective, misguided instinct to preserve the peace of her subjects by hiding the hurt away from them. Scara here isn't really her 'son', but representative of all of the people in Inazuma she would be causing grief by revealing Makoto's death. She throws Scara away to protect him (he's alone and sleeping like she plans to be), and forces Inazuma into constant stasis to keep everyone content. She fails miserably, abandoning Scara and inflicting prolonged misery onto her people, but I like to think the good intent was there.