Ushiromiya Battler...?

How about Ushiromiya Battler? He seems like a good fit.

"Ho... Battler, is it?" the Golden Witch asked, breaking into a grin. "That would be an amusing challenge, indeed! To get that stubborn human to acknowledge the existence of witches with a scheme like this would be truly interesting...! I look forward to the difficulty, and readily accept!"

In spite of her words, I noticed a bead of sweat running down her forehead. EVA seemed to notice it, too, and broke into an even bigger grin. "Aw, Predecessor... You need to work on your game face! I thought a little bit more of you as a witch than that... I accept too. I will gladly **** Ushiromiya Battler to acknowledge me as the Golden Witch!"

"Y-you're joking!" the other witch gave the other witch a look of shock, as though she had forgotten that was an option. "Player, the two of us are in agreement, but please: people read my tales and your damned story to see exciting battles between the witch, Beatrice, and her foolish opponent, Ushiromiya Battler! I won't forgive you if you choose this brat over the true Golden Witch, and your readers won't, either! And when I am vindicated as the true Beatrice, I might hold a grudge, understand...? I might level some particularly biting criticism of your work, get iiit?!"

"Ignore that old biddy who's about to become a figment of our collective imagination," EVA waved her Predecessor off confidently. "You're choosing me, right? I mean, you kind of already did. Don't you wanna support someone who worked their ass off to become Beatrice?"

"Like you know anything of my storied history, little girl," her opponent growled menacingly.

"Why don't you just give up and die...?"

... Hm. I love both of these characters, even when they're bickering... Truth be told, I want both of them to be acknowledged as Beatrice. But, the rules are already set up. The Beatrice I've chosen to support is...