Once upon a time, not so long ago, there existed a World of Magical Beings of which most of the Inhabitants of Earth were unaware. (Here the Author wishes to state, For the Record, that not all the Inhabitants called their Homeland the same thing as the Humans. Unfortunately the Humans were very Numerous and Loud and so they often got Their Way, despite the wishes of the Other Sentient Beings.) The World of Magical Beings consisted of several different species who tended to Respect Each Other's Boundaries (most of the time) as well as Humans who were Quite Different from those on the Other Side because they were Magical. These Magical Humans called themselves Witches and Wizards, a rather Sexist delineation that only served to Reinforce Ancient Pseudo-Patriarchal Gender Biases. However, most seemed happy with This Situation and so no one was much inclined to challenge the Status Quo.
Therefore, many Witches and Wizards were Highly Disturbed by the rise of the New Dark Lord, Voldemort, who seemed Hell Bent on ridding the Magical World of Witches and Wizards who were born to Non-Magical Human Parents. This was considered by Notables of Some Regard as Quite Odd since Voldemort (or, as the Notables called him, Young Tom Riddle) was himself the son of a Non-Magical Human Father and thus was considered a Half-Blood by those who were Concerned about Such Things. Still, this mattered little in the Grand Scheme of Affairs; what mattered was that his Misguided Propaganda was encouraging the Younger Generation of those who Concerned Themselves about Such Things to Terrible Heights of Depravity and Foolishness.
Finally it was decided by Important People that something simply Had To Be Done about the Situation and so one of the Notables, a Very Powerful Wizard by the name of Albus Dumbledore, convinced a Young Wizard of Potential Power to join those who Concerned Themselves about Such Things and learn whatever he possibly could. (The Author again wishes to Point Out the Glaring Sex Bias of the Powerful Wizard -- there were Witches who would have done Just As Well but who were Simply Excluded because some of the Notables feared they might be Seduced by Young Tom Riddle.) So it was that Severus Snape became Snape the Spy and spent years Ingratiating himself with the Dark Lord Voldemort and relaying Important Information to Dumbledore. However, one day Our Reluctant Hero was charged with what seemed the Most Daunting Task Outside a Triwizard Tournament.
"I need New Robes," announced the Dark Lord Voldemort. "Robes made of the Most Magical Material known to Man, Woman or Beast." (Here the Author wishes to state that despite all his Ignorant, Bigoted and Prejudiced Ways the Dark Lord was actually Free of the Sex Biases so Commonly Found in most of the Magical World.)
Few of the Dark Lord's Followers knew about Magical Materials and, unfortunately, Snape the Spy didn't disappear with the Others and so Was Charged with creating New Robes for the Dark Lord. Now, even Snape's Keen Intelligence had its limits and so he contacted Dumbledore. After much Debate the Notables told Snape to contact a Young Witch of Non-Magical Human Parents, Hermione Granger, who seemed to know Everything About Just About Anything.
Snape the Spy was a Tiny Bit Reluctant to follow this advice because he Remembered the Young Witch from his Teaching Days; back then she had been an Annoying Little Know-It-All and as far as he was concerned it sounded as if Little Had Changed. Still, he had No Other Viable Options. After much Brooding and Gnashing of Teeth, Our Reluctant Hero stuck his head in a fireplace and was soon rewarded with what turned out to be a Not-So-Annoying-And-Not-So-Little-Know-It-All.
Hermione had Grown Up and Snape the Spy (being a Mostly Heterosexual Male) was Quite Pleased with the Outcome.
Much Sexual Tension Followed as the Two began working on a new Magical Material in Snape the Spy's Private Laboratory, and Said Tension exploded three days later in a Flurry of Snogging and Shagging on Every Available Surface. In fact, they spent So Much Time Shagging that when Snape the Spy was summoned by the Dark Lord Voldemort they had no Magical Material with which to Pacify the Bastard, who was Quite Put Out that Snape was Shagging a Young Witch of Non-Magical Human Parents. However, Hermione was not a Know-It-All for Nothing. She quickly informed the Dark Lord that Snape the Spy had Created the Most Magical of Magical Materials and that only the Purest of Pureblooded Wizards and Witches could see the Miracle Cloth.
Needless to say, the Dark Lord Voldemort was Immensely Pleased and immediately removed to an interior room to try on these Magnificent Garments. Snape the Spy and Hermione the Know-It-All along with the Higher Ranks of Voldemort's Followers followed, only to be Confronted with an image of the dark Lord in the Most Impressive Set of Robes ever seen in the Magical World.
Or Voldemort in the Nude, depending.
"My Lord, they are Most Impressive," gushed his Followers as he Preened before his mirror, turning and twisting to get the Best View Possible. (It is worth Noting here that the mirror in question was the Mirror of Erised and that since the Dark Lord Voldemort's Greatest and Deepest Desire was the Most Impressive Set of Robes in the Magical World, this is what he saw.)
"Oh, yes," called Others.
"They are Most Fitting, Master," Lucius Malfoy purred obsequiously even as he Looked Askance at Snape the Spy.
The Dark Lord Voldemort was finally happy with what he saw and gathered everyone together and swept out to rejoin his Faithful Followers who gave a collective gasp at his entrance. However, they remembered the words of the Young Witch of Non-Magical Human Parents and made Flattering Remarks about the New Robes although each of them Privately Wondered if someone had tampered with their Family Records. Still, all Good Things (and Bad Things) must eventually end and the End came from the Least Likely Source.
"Father," whispered Draco Malfoy, a Former Classmate of the Young Witch of Non-Magical Human Parents. "Why is the Dark Lord cavorting amongst us with No Robes?"
For a Long Moment silence reigned as Each and Every Person (including the Dark Lord Voldemort, who by now was feeling a Bit Drafty) contemplated the Young Wizard who had spoken Their Thoughts Aloud. A shifting murmur arose from Amongst the Masses and things were beginning to look Very Bad for Our Reluctant Sex Fiends when, suddenly, the stuttering voice of Wormtail (a Derogatory if Applicable Nickname for a Wizard called Peter Pettigrew) rose up from Somewhere in the crowd.
"Our M-m-mast-ter is just en-d-dorsing a Robes Free Lifestyle!"
Had a Golden Snitch happened by at That Moment it would have been heard by the Entire Assembly. Then there were loud shouts and raucous catcalls as Witches and Wizards of All Ages tore off their robes and Danced Naked under the Full Moon. Thereafter the Dark Lord Voldemort gave up his Misguided Quest for a Pureblooded Magical World and changed his name to Brother Voldy, whereupon he began a Campaign for Dress Reform in the Magical World called "Magicals for Freedom from Voluminous Weighty Robes." It is still in existence today but has many Varied Factions, from those who advocate Sleeker Streamlined Robes to those who call for a Total Absence of All Clothing.
And as for Our Favorite Sex Bunnies?
Severus Snape gave up the life of a Spy despite the protests from the Notables that they needed someone on the Inside of MFVWR. He and Hermione held a mutually beneficial Joining Ceremony for Family and Friends and afterwards retired to the Not-So-Moldy-Pile-Of-Rocks, a.k.a. the Snape Ancestral Abode (though the Author wishes to Point Out that Hermione could have easily Afforded to Purchase a home had she Wished to do so), where they spent the remainder of their Long Lives brewing potions and shagging like Mad Rabbits.
But that is Another Story.