This is a beautiful story. Many of us crave the large male frame and penetration as young men but it is never validated or rarely even understood by anyone able to offer guidance. The man here took the right care of your anus your ego and helped you grow. It's a testing.
I had a very similar experience, but it was not my first. I was 12, and I was able to get upclose with my granddad's foreskin. As far as first m2m sex, because of the title of this group, I would not include my first experiences, but only my first love-making -- which I had with a boyfriend at 13.
I had lots of experiences from the age of about 12. I had a good friend at about 15 years old that I would have regular fun with.
First man on man fun was when I was 17. I was working and had just finished my shift. I went to the staff room to get changed where an older employee, about 37 was in there having his break. We were the only 2 in the staff room.
I went to the changing room and started to undress to get into my normal clothes. When I was down to my underwear he came into the room. He had a good look at my crotch area, I was nervous as hell and then he reached out and brushed his hand across my cock. The rest was a bit of a blur but I was hard instantly, he pulled out my cock and sucked me dry. Was an amazing experience and from then on I knew I was going to continue to enjoy man fun.