Heh.
Actually, my opinion is that he could have made a good protagonist of a similar sort of magical coming-of-age story; the difference is that he failed. He was sorted into an unpopular House, he made enemies with the popular kids, all of those tropes fell into place. But in the end, the bully own and got away scot-free, and Snape fell in with the only people who would talk to him and became a bitter old man before his time.
I find it fascinating.
This.
Snape started out as a young boy from a poor home, who fell in love with a beautiful girl. He came to school with her, determined to make a name for himself and win her heart...
...but he was alone. He didn't have anyone by his side but her, was in the most hated House, and was treated as evil from the start.
Despite that, he didn't give up on her. He tried to hold onto that friendship across house lines, tried to be a good man...and was metaphorically kicked in the face for it, courtesy of James Potter.
Eventually, he broke. He lost Lily, because he was trained to hate and fear everything around him...and was infinitely ashamed of his perceived weakness, compared to the marauders. She tried to help him, but he couldn't stand be saved by somone he felt he was supposed to protect...so he hurt her, and she ran into the arms of his enemy.
He joins the only people who will have him, the Death Eaters, and kills muggles (recall that, in his mind, muggles are "people like his father and Petunia") and enemy witches and wizards (that is, to say, "people like James Potter"). Eventually, though, he discovers that his master intends to kill Lily and her family. The child was the target (so there was no hope of saving it) and James was James, but he used the good will he'd earned with Voldemort to get him to spare her (the girl who walked away and married the man he hated most, you recall).
Voldemort tried, but she made him kill her anyway...and then died himself.
Snape had lost the only two people who gave his life meaning, both in one night...and thus he let Dumbledore take Voldemort's place.
He taught at Hogwarts...and saw every Gryffindor as one of those who abused him. Likewise, he saw himself in every hated Slytherin.
Then Harry showed up...the very image of the man who destroyed Snape's life. Perhaps, had he been in another house, Snape would have given him a chance, but he was a Gryffindor...and thus, in Snape's eyes, he was everything that James was.
He saved his life anyway, time after time, because he was Lily's son.
Severus Snape was a good man...but only in the strange world he saw, not the one others perceived. He protected the victims, punished the abusers, and slew the monsters of the world...he even protected his love's child, despite her turning against him.
It's just too bad his perception had been warped so badly by a childhood of abuse and betrayal.