There were some really good comments on my first thread:
Is love enough of a reason?
So I thought I'd try a followup.
If Lily would have returned Snapes love, or Snape had loved someone else that returned his love, what do you think would have been different?
Would he have joined Voldemort?
Would his cruelty and bullying still have been there?
Snape as a father?
Would he taken more care in his appearance?
Would he sing, would he dance?