It is fun working with people. The challenge for us photographers, even when the subjects are not in the mood is to turn their mood around so their facial expressions, body language and acting will reflect the emotions you want to capture. You have to work closely together with your subject.
Now the real challenge start when you have to deal with more than one or two people. Big groups are interesting to work with. You have to prepare them to what is going to happen. I usually keep a short briefing before the pictures. Of course, everything is planned in advance e.g.: where people have to stand etc.