"A sympathy for Slytherin, eh?" said the small voice. "Interesting. You could be great, you know, it’s all here in your head, and Slytherin will help you on the way to greatness, no doubt about that. Brilliant too, though people will underestimate you. Easy to be manipulative when you're underestimated," the hat hummed, sounding now like he was straying to Ravenclaw. Harry hadn't even realised Ravenclaw could be an option for him. 