just look at it this way...would voldemore, he who must not be named, you-know-who be a HUFFLEPuFF? hes kinda stupid (to me) to be in ravenclaw and i wont even have to mention the possibility of him being a gyfinddor (like absoleutley no WAY)! so even if hes half he can be sylvhterin, he sure fits it doesnt he? and the hat also wanted harry to be one too and hes half like voldy...