I'll never understand the fascination with Harry/Snape.
How does the utter contempt a teenager feels for a man 20 years his senior and the complete loathing the older man shows the boy translate into affection? It doesn't. To think it does is a frightening stretch of the imagination to say the least.
Said animosity does not come from unresolved sexual tension. I've, sadly, experienced the level of hatred Harry and Snape feel for one another. At no point did I want to kiss or cuddle with the man. I sorely wanted to kick the man in the balls.
Harry/Snape is the slash equivalent as Hermione/Draco. /Hate does not equal love/. It equals hate. If someone loves a person and they express it through words and acts of hatred, that's a sure sign of mental and emotional instability and will more likely than not lead to physical and/or mental abuse.
Please feel free to write slash, just don't write such a deplorable pairing.