I've got it all figured out with the intercessory prayer thang. (note the sarcasm)
A few months ago, Guitar Man was having great difficulty with PEACE. He was easily frustrated. Slamming stuff frustrated. All the time.
Then, I started a 30 day Novena to St. Joseph for him. About 1/2 way through the novena, I asked my counselor for suggestions on dealing with him.
I never had to use what she suggested because he calmed down and I turned into the poorly behaved one. Then the next time I went to counseling, I had to admit it and she said, "Kiiiiimmm" in a sweet, gently chastising voice. We talked about my anger management issues and I'm working on it.
Tonight, I was mildly irritated, let Guitar Man know it and he wouldn't fall for it. He stayed calm and completely diffused the situation. It could have easily blown up.
So, the lesson is: pray for your loved ones, God may grant them graces that end up helping you more than the prayer helped them.