Well... "Rule over" has such a nasty sound to it.

I'd call it "control".

Dutiful or not, isn't that sort of sisterly relationship

going to hinder her independence?

We aren't strong like you, Raiko-san. Nor are we wise.

Only together can we barely stand on our own.

I have to command her so we don't get separated.

Well then, what would you do if I asked her to group up with me instead?

We know she adores me. That's easy to make use of.