I've found there is a limit to everything under the sun. That old saying "too much of a good thing, is a bad thing" is dead on.
In example, having someone's back is a good thing...in moderation. Stalking someone, bugging their phones, and suggesting the numbers of local practitioners that "may have what you need" is clearly NOT a good thing.
Despite any inane reasoning or justification you may have built up in your mind, the person you are "looking out for" won't be appreciative when they notice you across the street with binoculars. In fact, they'll probably call the police and/or bust a cap in you. No joke.
I say these mildly disturbing things because I have experienced this rare type of lunacy first hand. Maybe not to this extent, but I digress.
Heed my warning: keep yourself in check, and let your friends do the same.
Granted, if you see your friend purchase what appears to be a bag of snow from a hooded figure in a dark alley, feel free to hide in a bush and find out what's up. But besides that very unlikely situation, there's no reason to drive your large white van around your friend's neighborhood wearing infared goggles.
Because he or she WILL have you arrested or killed.