Sometimes things just have to smack me upside the head.......

[Carol]

Mary wrote:
<snip> 
> The other Aha! moment was when I finally realized why Snape was so hard on Neville. If Voldemort had chosen Neville instead of Harry, Lily would be alive. 

Carol responds:

And Snape would still be a Death Eater!

Seriously, though, do we know for sure that Snape knows about Neville as a potential Prophecy boy? Maybe he just can't tolerate incompetence, especially when that incompetence endangers other students as it does in Potions class. In Neville's very first class, he melts Seamus's cauldron and drenches himself with a potion that's supposed to *cure* boils and instead, in his case, creates them, and he continues to melt cauldrons through several more books. Also, as we know, Snape hates both weakness and cowardice, and he may regard Neville's (understandable) fear of him as both.

Carol, just presenting other possibilities