She panics

After her orgasm, the strength Siara used to fuck you with leaves her legs and she releases you from her grasp. When you step away, your already deflating dick slips out of the abbess’s freshly deflowered pussy. When Siara tries to sit up, the weight of her horns surprises her and weighs her head down. She groans and rolls sideways to get off the table before standing on her feet.
“Ugh, why is my head so heavy?” She wonders.
She brings her hands to her head and tries to feel for the source of the extra weight. At first, she is confused when she feels her hair. She had expected her veil to still be there. But she is even more confused when she feels two boney extensions attached to her skull.
In her eyes you see confusion give way to shock and she says, “No … no no no no no no.”
She slowly walks her nude body up to a mirror in her room to check herself out. The veil dangling on her one horn as she walks. She stares at herself in silence for about half a minute. She takes in the fact she now has black lips, eyelids and horns.
Then she jerks her head to look at you, the motion was so quick it sent her veil flying and says, “You said nobody would find out!”
“To be precise.” You correct her as you put your dick back into your pants.” I said I wouldn’t tell anyone.”
“Oooh my god.” Siara says as she starts panicking and returns to the mirror. “How am I going to explain this to the others. Jennifer and Angelica. They are never going to understand. And Miryam …”
Then realization dawned on Siara who slowly turns to you and says, “… You fucked Miryam.”
“You, me and Miryam are the only people who know sex with me results in corruption.” You calmly say. “I already promised not to tell anyone and I doubt you are going to tell. So, if Miryam stays quiet your secret will be safe.”
“Safe?” Siara asks with anger in her voice. “Did you even see what massive horns are sticking out of my head? I’ll be lucky if I can still fit through the door with these.”
Siara turns back to her mirror and laments, “Oh, why did I have to break my vow.”
You walk up behind Siara and say, “It seems like you need some time to reflect on this.”
Siara looks at your reflection in the mirror and asks, “Ya think?”
“And if Jennifer or Angelica have need of you, they’ll come right here.” You continue.
“Oh shit.” Siara curses. “I need to hide.”
“I’ll get you somewhere safe.” You suggest.

You take out your phone and contact Talith. After her tryst, she had apparently gone straight to your lair. Then she saw you screwing Siara on the security footage. After congratulating you, you ask her where Angelica and Jennifer are. Talith informs you that they are currently at the bathroom. Perfect, that means you can get Siara to your lair without them seeing her. In the meantime, Siara has picked up her clothes, veil and panties included, and put them back on. Then you and Siara get out of her room and sneak all the way to your lair. All the while, you were holding Siara’s hand. Down there Talith is already waiting for the two of you.
“Oh, hey Siara.” Talith welcomes the head nun. “Nice horns.”
“Don’t talk to me about them.” Siara says in an annoyed tone. “Unless you know of a way to make them disappear.”
“Mmmh, sorry sweetie. Those are there to stay.” Talith says.
You guide Siara to the bed where she sits down on her knees.
“It’s done.” She laments with her face buried in her hands. “My life is over. I’m ruined.”
Talith helps keep the security camera’s a secret by asking Siara how she got this transformation. Siara, in her state, spills the beans and tells the succubus everything that happened.
“Yeah, I never understood that vow.” Talith says. “Why on earth would a god first create humans and instill into them a yearning for sexual gratification, then command his most ardent followers they can’t engage on that gift he put into them to begin with. It would make far more sense if your religion permitted sex.”
“Yeah, why not take your little convent and make sex permissible for the members.” You suggest. “No more vow of chastity to worry about. Just participate in normal human nature and experience all aspects of life.”
“Jennifer and Angelica will never agree.” Siara says. “Even, if they did, the horns will still be there as proof I cavorted with demons and they’d judge me for it.”
“Why not suggest you’re doing the same as Miryam.” Talith suggests “She too has allowed demonism into her life and she’s still the same person? Or what about me? I am a demon who cavorts with nuns. If I meet you halfway and you meet me halfway, surely it should convince plenty more demons to consider joining your faith, right?”
“I … I don’t know.” Siara say. “I can’t think like this. I need to be alone.”
Talith looks at you, wondering what your opinion on this matter is. You believe it is best to let Siara be for now, so you nod at Talith. Both you and the succubus lock to doors to the side rooms. No need for Siara to arm herself or discover the security station. There is no harm in her finding the summoning circle. There is not much she can do with it. After that, you and the succubus exit the room and leave Siara alone.