So, recently my youngest brother (he's 16, I'm 26) had a party of a classmate. Mom and dad did allow him to go, and he did just fine. He lived by the rules, he sent a message when he arrived safely and one when he started the bicycle ride back, was home sort-of on time. He only missed one rule: No alcohol.
Mom and dad were tired, so I promised I would stay up to make sure my brother arrived safely home, or else wake them up. When he came home, he seemed off to me, but I brushed it off as him being sleepy. Yesterday, he confessed to me he had 3 beers at the party, and he wasn't sleepy but halfway drunk.
I didn't push him for that information, he told me out of the blue. I'm glad he thinks I can be trusted with the information, but at the same time, I was at a loss for words when he told me. Now that I've had some time to think about it, I feel like I should have a talk with him about this.
I don't know him as being an irresponsible person. Generally speaking, we can say that his friends weren't the most responsible people, and having drunk only 3 beers might have been quite the achievement when counting peer pressure.
He's 16, he's allowed a very occasional alcoholic beverage at home when there's a special occasion. But, he's not allowed to drink alcohol when he's not home. Especially not when he has to cycle home alone, on a road along a canal.
I'd like to have a talk with him about this, to express my worries and hopefully address some of the dangers he took, and make him realize he was being irresponsible, and that if mom and dad ever find out, he might well face serious consequences. At the same time, I want him to understand that I don't want to ruin his trust in me by telling my parents. I hope that by doing so, he feels confident to tell me next time something happens, when he's at a party with the wrong people, or even call me to pick him up when he's too drunk to safely get home.
But, I have no idea how to say this without either sounding like my mom, providing a sermon on irresponsible behavior, or sounding like I might run off to tattle-tale everything to mom and dad (I won't!).
What do I have to keep in mind when I want to have a fruitful talk about this with my brother?
Tiny disclaimer: Until a few years back, the legal age for drinking light alcoholic beverages like beer was 16 years in The Netherlands (so my oldest brother and me grew up being allowed to drink at 16), in 2014 it got raised to 18. My parents are allowing my brother to drink at home on special occasions, as far as I know this isn't illegal.