Crowley used to be a man. He was this weak, fleshy being filled with self-loathing, or something like it. If memory serves him right, and this is where it gets sketchy, he sold his soul for a bigger dick. Clever.
He could tell himself that it all worked out masterfully, that he's ratted his way up the chain of command from Scottish weanie to suffering soul to small-time demon to King of the Crossroads to King of Hell. But really, it doesn't mean much if he's going to spend all his time in the Winchester's basement.
He had thought he had the two pea-brained meat lumps under his control with his purgatory snatching plan and then his demon tablet plan, but apparently not. They bested him with brute force and handcuffs and at this point, Crowley is so disgusted with himself he, he almost thinks he would deserve to be fired as King of Hell.
It's not so bad here though. If he were to delude himself, he would have to say that at least here, when someone talks to him, they're not wasting his time. Not like all those mindless demon drones who tell him about failure and confusion (probably a few too many rounds with the brain-grinder back home), rather than regrouping and getting the damn job done. Here, the Winchester boys are all business, asking- demanding- answers and threatening him pretty effectively. Well, not really, but they are doing well considering that threats don't work on him.
The thing is, Crowley is getting bored. He sits, tied to this chair, all day and all night and it makes his skin itch. He is surrounded by whispers and tingling need and he does not like it at all. He bides his time though, humming under his breath and daydreaming about the pit and decidedly not thinking about what Sam's blood did to him.
The times Kevin visits him are delightful. Kevin is new to the game and not ready for the intensity and nastiness at all. He's learning, growing a shield against harsh words, but as long as he still loves that feisty mother of his, Kevin will always be under Crowley's thumb. Crowley likes the rush of power, his ability to dig under Kevin skin without any physical skinning. It's fun.
And then he's alone again, bored and waiting, engulfed in loud silences and a burning need for something.