I had a 82 year old lady once on a trial flight who refused to leave go of the controls.
She had an iron grip on the yoke and after the TO and 10mins the option of her doing the landing was out.
Just as we entered the circuit I gave the "I have control" and she wouldn't let go. After repeating 2-3 times i peeled her fingers off the yoke. She never said a thing. Then as I turned finals her hands went on again like iron. Missed app then had to decide what to do. First idea was hit her round the back of the head with the fire exingisher vetoed due to cleaning the blood up afterwards. Next idea which i used was peel her hands off again then pitch up into a 15deg climb while pulling the seat release on her side. She went sliding back and couldn't reach the controls. Then did a very abbreviated approach before she could get the seat forward again.
Lesson learnt is don't go by apperances with trial flights the hardest drug dealing manicas will cry like babys with only 10degs of bank and the old grannys will have you spinning and stressing the wings.
Not even going to recount the vomiting on finals storys, luckly i had only 2 but they were trumatic enough. There is nothing like atomised vomit all down your back with another 4 hours of flying to do.
MJ