So, your session begins and you instantly secured in bondage. There's a knock on the door.
The door creaks open and you look up in surprise at who has walked in to replace or join her
Who is it? (I'm thinking more real person from your life rather than celebrity) Neighbour, ex, former teacher etc
For me I'd say my wife. Maybe she found out about my visits and arranged to surprise me when I'm my most helpless and caught off guard