Spoilers ahead for Fire Emblem: Three Houses:
Rhea’s nothing like a Captain Planet villain, IMO. She’s as tragic and sympathetic and complicated as Edelgard if not more so, though you only really find out her backstory at the end of Verdant Wind. I won’t say she doesn’t have some responsibility for the systemic evils of the game, but I don’t think it’s anywhere close to nearly all of it. (I guess some of this depends on how much power one perceives the Church as having, and IMO while it’s considerable it’s nothing close to absolute.) To me, the game makes clear that the main cause of those systemic evils isn’t so much one particular person as it is human greed and lust for power in general, but, if you’re going to pin it on one particular entity, IMO it should be Those Who Slither in the Dark. The actions of Rhea, Dimitri, and Edelgard are all rooted in their own trauma, and for all of them, the source of that trauma is, ultimately, TWSitD.
Anyway... to comment on the picture, I like it and I wish there was more out there for this pairing generally. I suppose the way it’s kind of incestuous from both directions but also technically not puts people off, though.