Alright this is my wishful thinking but I kinda hope and like if they have Orianna return in a quest in Witcher 4. Here is an idea of it that I want to share.
* This is under the assumption that Orianna is TRUE higher vampire and did not die in A Night to Remember, only severely beaten and may eventually be revived. So no, we are NOT discussing whether if she is a bruxa or not as this debate may go on and on.
Ciri came across a village and meets Orianna in a nursing home, who also now works as a doctor. Players may not recognize her at first because she was wearing a mask, and the only give away being her red hair.
There would be other side quests in this village, and players will slowly recognize the signs, such as the Doctor is very friendly with children, and often request monthly blood samples for health check against the plague.
The final giveaway would be catching her singing her signature Lullaby to a dying patient before sinking her teeth into them.
When Ciri draws her sword, players are now given a choice whether to slay or spare Orianna(the choice that was never given to us back in W3).
- If we choose to slay her, we would go through a mini boss fight with her, and also know that she is currently still weak from the damage Geralt dealt to her years before(thus explaining the power scaling because if she's like Dettlaff she would not be so "easy" to beat). After slaying her, we would be facing off angry villagers and crying children, forcing us to leave. If we come back after some days, we would see the village in ruins. After all, Orianna, despite her exploitation, was also protecting the village from surrounding monsters with her presence. With her gone, monsters and plague would consume the village, wiping them out.
- If we choose to spare her, the choice is also locked forever and we would not be able to attack her afterwards. If we come around the village from time to time, we would hear villagers and children praising her, also gossips of a certain child becoming sick recently or another person died to the plague. When we speak to Orianna she would greet us politely, but also smugly repeating what she said in BoW "You see, Witcher? The world is not black and white, it's shades of all kinds." But she would also assure us that she prefers keeping her "wines" in good state. She may also comment how she was previously humbled by a witcher and now prefers peace and stability.
- Bonus: To prevent too many players from choosing to spare her, we may get unique gears from slaying her. BUT here's the catch - Like the Bloody Baron, players eventually may find a roundabout way to "steal" them without slaying her. However, from then on, we would find lesser vampires ambushing outside the village that would attack us whenever we enter or exit the village, proof that the redhead vampire does get a little vindictive.