A young man came in and wanted to talk about his friend with bipolar, who, when he gets manic, can become uncontrollable.
I said that the idea of controlling dangerous behavior can be problematic.
The need to control someone else’s recklessness can lead towards confrontation and anger, which often does not work out well.
I thought of the often repeated story by American Aikido master Terry Dobson.
Here is an audio version read by Ram Dass.
The story is about the trap of wanting to control bad behavior. And what happens is a vivid illustration of the non-violent alternative – which is first joining with the other person, sharing their view of things in a way that is experienced by them as understanding, and then finding a way of redirecting them.
The hook that can make this hard is the strong desire to prevent danger… especially with someone we love. But that desire can sometimes stand in the way of effective action. 
Think of the difference between a karate move (responding to a blow with a block or another blow) and an aikido move, which involves coming in towards the person, joining with that person’s movement and then redirecting it.
Aikido disarms the opponent whereas Karate enrages him.
The techniques and images can serve as a reminder of the basic principle.