Deputize her

"Greetings, Marianne von Edmund." Edelgard said, attempting to sound casual. The blue haired girl jumped and turned to look at the future empress.

"O-oh, hello Edelg-" She stopped, speechless as she looked at Catherine. The naked Knight had jogged over to a spare sadle and picked it up, strapping it across her own waist. Bending over so she was on her hands and feet, she 'galloped' over to a water trough and dunked her hole head in, shaking her tan rear for the two of them.

"Don't mind her." Edelgard said with a wave, reality bending so Marianne didn't mind the knight's strange new deranged perversions. "In any case, I know about your crest." Marianne visibly flinched at that. "Maurice was a hero, and the church suppressed him. But I decree that to be no more!" She gave an authoritative point at the girl. "I hereby give the the title of Secret Royal Deputy to the Empress! You are more confident now, and enjoy near free reign to follow any erotic desires you have, unless they would supersede any of my commands. No one will find your actions odd, and any order given will cause their body to obey! Only the subject will be aware of any strangeness as a result; the others won't think anything of it." Edelgard commanded with authority.

Marianne suddenly felt something wash over her, a newfound confidence from Edelgard's granted title. She turned her head to look at Catherine, occasionally rising her head above water to give a mute whinny and breathe before dunking it back into the water trough to drink. The wielder of the Crest of Beasts looked her over, licking her lips...