Seems it is not so uncommon after all
I have been married now for almost 4 years. My stepdaughter, Christine (not her real name) is 16. For the past couple of years I have seen her grow up into a fine young lady and, I am embarassed to say, have started looking at her differently ever since.
Her hugs and kisses have started to arouse me more and more, and at the same time her dresses became less and less conservative when she is around me. This particular instance happened a year ago when her mom away at her sister's.
It was a warm and humid summer's night and I was shirtless wearing only my shorts watching TV in dim light as always. Christine joined me sometime later and sat on the adjacent sofa next to me.
She was in her nightie and it was quite obvious that she was braless. I soon started getting an erection and it was difficult to hide it because of my shorts. She also noticed it but kept watching the TV. I badly needed to relieve myself but could not dare stand up. Christine, on the other hand, now started glancing more frequently at my shorts instead of the TV, which made it harder still.
She started getting more fidgety and adjusted the elastic band of her underwear. In the dark I could make out that her hand then slowly started moving inside it. I too thought she would not be able to see me and started rubbing through my shorts. Soon she left and I heard her going into the bathroom.
After I had finished rubbing enough, I thought I better go and finish it off. As I stood over the commode and started masturbating, I saw that Christine had hung her panties on the towel rod. Carefully I picked them up and smelled them. They were fresh with her juices. I licked them and then wrapped around my cock and came into them.
After washing them, I kept them back in the laundry hamper. Next morning while going to the shower, I found another pair of panties on top of the hamper. I could not control myself and took them to the bathroom to jerk into.
This has now continued for about a year. Whenever mom is away, her panties always seem to be right where I can find them. No wonder she is enjoying the fun.