Explain this passage

[potioncat]

No: HPFGUIDX 180678


> 
> Carol, noting that both Harry and Ron regarded the Half-Blood Prince
> as a genius (too bad he couldn't have been their contemporary and
> their friend)


Potioncat:
Interesting isn't it, that these two Gryffindor boys liked this 
Slytherin?--or what they knew of him. They didn't find the magic to 
be "dark" or horrible. It reminds me again of the excuse given that 
James didn't like Severus because Severus was into Dark Magic. The 
real issue was that James disliked Severus because of a Slytherin 
bias.

I have to wonder again, if the Hat had offered Gryffindor to Severus, 
if he would have taken it? Would Lily being there be enough, or would 
James being there have been too much?

Potioncat