User blog comment:EmpyreanSmoke/Finding Crowley/@comment-98.243.104.144-20150124000911

I wonder if it depends on the power of the demon. Perhaps lower demons, the average black eyed demon for example, have to come when they are summoned. But since Crowley, being the King of Hell and Azazel, being just under Lilith and so close to Lucifer, aren't restricted by summoning spells and can choose to appear when summoned. Also, with Crowley's knowledge of magic, he might know a spell that counteracts a summoning spell and makes it so he doesn't have to show  up unless he chooses to.