Though he refrains from actually pressing up against the door, it kind of sounds like he is. Like if a cat could actually use a cajoling voice instead of meowing or sitting on you until it gets its way, this would be it. There's a trace of self-mockery in it, though, too. Or maybe just plain old mockery.

"I'll be as nice as I know how," he promises, sly and meek. It doesn't even occur to him to try using his powers — not through this door, anyway, but voice has always been the primary medium for influencing others. "No, seriously, I'll be good. Maybe not really good but reasonably good. How's that sound."