The unconventional presentation of the protagonists and antagonists in Psycho is all part of Hitchcock's masterful manipulation, his gleeful manner of misdirecting attention and subverting expectations. Yet he doesn't merely subvert by way of conveying story points; he does it via the actual narrative structure; by exploding movie conventions.
The presentation of Norman Bates (Anthony Perkins) represents another shattering of tradition too. Hollywood often lives by the edict that what is beautiful must also be good. And young Anthony Perkins, like Janet Leigh, is certainly beautiful. He is innocent, boyish, graceful, handsome and charming. Simultaneously, he is a brutal murderer when "possessed" by Mother Bates. The film asks us to countenance competing visions of Norman, that he can be both innocent and guilty; a good boy and a very naughty boy at the same time.