Cressida and Leon
Substance abuse happened for any number of reasons. Somehow, she doubted peer pressure was involved with John's. She noted his stays in rehabilitation centers. He was too focused to be a drinker. He must have been using something else. "John seems to have issues rooted in a desire to prove himself, " she said, "specifically to his tribe. To live up to your legacy." She didn't want to say outright John was using but she would have to imply it.
"You know you were a powerful witch with an uncanny ability," she said, "so I worry that he might have taken steps toward trying to meet that standard." It wasn't Leon's fault though. He was a witch with a gift and he was focused and strong. He was a head above many other witches his age, likely why he and Barclay were good friends and likely friendly rivals in their magic.
"You also know John in a way I don't, even if your time with him has been just as long as I have," she said, "you have a different perspective on him than I would."