@ Archpaladin Not all demons are evil, vicious, angry and dangerous.
Mostly they are cautious, wise and sometimes stubborn. But the demons are same as angels and they want to be treated with respect and if one summoned it doesn't like the idea of you commanding him what to do (Your voice should be calm and strict). They like to be treated like gods.
Fear is something that should not be felt or shown on the summoners face because than demons get evil, vicious, dangerous and therefore they will use you as their "toy".
Anyway every demon likes a good bargain ;)