WIY, when I was in HS, one of my friends was going down a bad path. She wasn’t doing anything terrible yet…but she was getting worse and worse.
Finally, she hitched a ride in the back of a van (seats taken out) with a guy I knew did drugs (I wasn’t sure if he was using at that point).
I went to her father. Her father and I were very close and I knew he could handle hearing it and would react appropriately. My friend asked me point blank if I had told her father and I said yes. We are still super close to this day.