Hello guys. About a month ago, I attended the wedding of one of my best friends, who's 25 years old, and whose name I will not be revealing, to protect her identity. I have been feeling guilty ever since, not because of the ceremony itself, but because of something I saw... During the party, I went outside to make a phone call, and I saw my friend's little brother (12 years old) surrounded by some teenagers, who were saying things like "Do it", "Don't be a (...)", "Man up" to him. I got next to them, quietly, and, to my surprise, one of the teens was handing him a cigarette and lighting it up for him! He tried it, and then they noticed I was there - of course, they tried to hide it, but I had already seen it. I reprimanded them for encouraging him to do something so nasty as smoking... Later on, when I got a chance of talking to him, he promised me he would never smoke again... but I was left worried. The problem is that I did exactly the same thing as a child - when I was 11, I was a victim of peer pressure, having been forced to smoke, which I repeated until I was 13, despite having been warned to stop multiple times before... Yesterday, I went to the inauguration of my friend and her fiancée's house and I found her brother outside, smoking once again! I confronted him yet again, and threatened to reveal the problem to his parents. He promised he would never do it again, but I just knew those were empty words. What am I supposed to do now? I'm already regretting my decision to not do anything about it at the wedding... maybe he would've stopped by now.