One of my callers told me that when he was in his early teens his mom remarried and the guy she married had a son his age and they were then step brothers, expected to get along and get along they did, a lot better than their parents ever would have known about of approved of. It was so easy for them to get time together right under their parents noses, who would question two step brothers spending time together for hours on end? Certainly not their parents.
They were both horny young guys with a curiosity for all things sexual and it started off with them just watching porn together and jerking off in the same room, then helping each other with their hands, then their mouths and then full on fucking and without any worry of being caught, since their parents had no reason to think anything was off. The late nights after their parents went to sleep and they snuck into one another’s rooms, with a stiff cock that needed attention, and the one they went to was only too happy to help them suck it or stroke it off.
This went on until they both left for different colleges and then they only got to play when they came home for vacations, so their time was less, and they both moved on, but for several years they had lots of sex and came countless times as their parents innocently sleep in the room down the hall as their son’s fucked and sucked each other silly. The secrecy was also a big part of the turn on, it was very hot and furtive for all those years.