As a player I tend to be hunting virtually the entire time i am logged in. That means that as soon as I conjure I feed my demons, ie go to goblin village and let them grab up a dozen weapons or eat a village full of corpses, this takes like 2 ticks, you can even have your familiar do it while your conjuring and just walk through after. Then as you are teleporting around anytime you land near a weak mob that might please your demon take the half second and off them. In this way your always making mr demon happy. I don't sit around for any longer then it takes me to heal up so in that way I always kept my demons happy just constantly feeding them low level stuff.

Now devils were the tricky part, if I could gear up over 1k hp it wasn't a big deal but under that and the ratio of resting to fighting just made them difficult to manage for me and keep hunting.

so at the end of the day if you don't want your demons to be mad feed them. Feed them often, like every couple of ticks and you will be fine.

I had a tribunal conjurer who used almost exclusively demons (and having both the demon conjuring edges was sooooooooo nasty to get hooded demons with only 400 mana in conjuration) aside from when they got super pissed due to failed bindings i had a demon turn on me once ever so there you have it. (devils on the other hand did not fit my hit and go tactics and ice devils were almost a sure death sentance for me)