But if you just purely look at Snape's character's set up and function in the story, it still fits that type of role perfectly. No matter it's peer or not, the role is still the closest to the "bully/enemy turn allies/friend" type than anyone else, simple as that. Beside, since you're getting picky about it, the "bully" in DB is nothing like Draco either, their archtypes are different, he is not the "rich spoil previlage kid" arhetype that Draco is, nor the DB's bully sided with the villain and his beliefs either. You don't think those would makes any difference?

And we must have very different definition of "enemy" because to me Snape IS very very much Harry's enemy throughout all five books (enemy doesn't necessary have to be on the oppositing side nor different beliefs nor be the "villain"). I'm not sure if Snape is a secondary protagonist (since definition vary), but I think he has the most conflicts and links to all sides of things and characters right after Harry.

So anyhow I still don't see how JKR being a female has anything to do with her intended plan for Draco's character. Are you suggesting that perhaps female are less likely to befriend or forgive their ex-bullies than male or something?