It's good to fantasize once in a while, I suppose.
Any ideas how would you wanted story to continue?
I made a headcannon for a possible ending, here goes:
Since the game established that one master can't easily take control of another master's servant, that final scene with the detective changing sides doesn't make any sense, she doesn't feel pain or faint like the other cases.
So the detective is probably faking it to gain an upper hand and stab the doctor in the back ("be the best you can be" even an actress/lier). She does that: kills the doctor with a stolen gun while pretending to start a blowjob on him or something. The doctor's servants goes into shock, paralyzed, having their link to their master severed and faint. Then the detective frees the MC and the family, everybody hugs. The MC manages to convert the doctor's servant after.
Final scene: they all go to the mansion and happy harem orgy. The End.