It was not something quite as innocuous as the flapping of a butterfly's wing that changed the fate of the wizarding world. Rather it was the choice, in so much that they make choices, of a western honey bee that would alter the course of the lives of a great number of people, wizard and Muggle alike. It was on July 30th, 1991 that the honey bee in question was approached by a small child of seven years, though the bee, had anyone thought to ask her and had she been capable of answering, would have said she was being attacked by a giant monster. In another lifetime the bee would have stung the child to defend her hive, losing her stinger and life in the process. However on this particular day the bee was feeling slightly less brave, or perhaps just less suicidal, and was rewarded when the monster shortly went on its way, leaving her to return to her normal routine of gathering nectar.
The boy, having successfully retrieved his ball, returned to his friends to continue their game of football, completely unaware of how close they had been to having to call of the game due to his severe bee allergy. As it was, they were able to play for another fifteen minutes before a solid kick and poor aim sent the ball over a fence and straight into the window of a nearby house.
The window did not break, of course, as this particular house belonged to a wizard. More tellingly, this house belonged to Severus Snape, and while many other wizards might leave the windows to break and be fixed with a quick Reparo charm, Severus preferred to charm the glass not to break in the first place. All too often had Severus found a problem much harder to fix than he would have thought – assuming fixing it were indeed possible – for him to not do everything he could to prevent them from happening. Whether or not this philosophy was one that need be applied to household windows is not something he spent much time contemplating.
Therefore the sound the ball made when it hit the window was more of a loud thud than the shattering of glass, though in the long run either sound would have been enough to make a difference. For whichever noise it was, it was loud enough to startle – not that he would ever admit to it – Severus out of a state of deep concentration. Glancing up from the book he was reading to look at the clock, Severus found himself somewhat grateful to the ball that had most assuredly not startled him. For the book he had been reading was a particularly engrossing one on complex potions theory, written in Russian. The intensive amounts of time and effort that it actually took Severus to read Russian, coupled with the length of the books chapters meant it would have likely been another hour or so before he finished the chapter he was reading and thought to check the time. On a normal day this might not have mattered, but today he had a meeting with the Headmaster in ten minutes, meaning the extra hour lost would have made him very late. And since Severus had stop believing late to be better than never on the night of October 31, 1981, he would have had to send his apologies to Dumbledore and not have gone to the meeting at all. As it was, he had been interrupted, so he carefully put away his book, making sure to bookmark his page, checked to make sure he had anything he might need and a good many things he probably wouldn't and flooed to Dumbledore's office a full five minutes early.
Severus stepped out of the fireplace and into the office proper, brushing the soot off himself. The office seemed much the same as it had when Severus had first been in it, nearly sixteen years ago now. The sleeping portraits lining the circular walls and silver instrument whirring and puffing on spindle-legged tables could have been a scene out of any of his memories of visits to this office. This lack of apparent change reflected itself in the office's owner, who appeared to Severus to be almost frozen in time from the moment he had first saw the old man at the Welcoming Feast of Severus's first year at Hogwarts.
"Ah, Severus, good of you to come. Please, have a seat," said Dumbledore, turning around from where he had been admiring his phoenix just moments before. He gestured Severus toward a vacant chair before seating himself behind his great claw-footed desk. "I'm afraid I have a small favour to ask of you."
"What would that be?" asked Severus warily. While he had meant it all those years ago when he promised Dumbledore he would do anything for him in return for the old man's help, it did not mean Severus actually enjoyed doing these "small favours." Particularly since Dumbledore's idea of a small favour more closely aligned with Severus's idea of a large undertaking.
Dumbledore watched Severus for a minute, as though gauging how the other man would react to the favour required of him before replying. "I need you to give a home visit to one of our prospective students."
"I was under the impression that it was Minerva's job to give the home visits to the Muggleborn students. Besides am I really the most capable member of the staff you can find?" Severus asked. Even in all of his optimism, Dumbledore had to be aware of Severus's… distaste for small children. While Severus might understand the necessity of being a teacher when his sole protector was the Headmaster of a school, Severus didn't actually enjoy interacting with children, especially the younger ones. This made it rather difficult to understand how Dumbledore thought sending him to some child's house was a good idea.
"Yes, well I'm afraid we've run into some… unexpected delays with this one," Dumbledore explained looking strangely uncomfortable. "I didn't anticipate needing to visit this particular child at home and the necessity of it has only recently become apparent. Because of this Minerva didn't schedule a visit to this child, and isn't able to fit it in at the last minute, and none of the other staff, aside from Hagrid, were available on such short notice. Besides which you have some unique qualifications that make you perfect for this particular visit."
Unique qualifications? That sounded decidedly suspicious. Still if it was between him and Hagrid… "Who is the child?"
"Why Severus," Dumbledore replied, and Severus allowed himself a brief moment to wonder at how he could go from uncomfortable to positively beaming in such a short span of time, "it's young Harry Potter, of course. After all you did swear to protect him from harm, which makes you rather perfect for the job, wouldn't you say? Plus I was hoping that the fact that you already know the boy's aunt might facilitate things a bit. You remember Petunia, of course?"
Severus's mind, which had come to a stop at the mention of Harry Potter, roared back to life upon hearing the name of that foul woman. "Petunia Evans? You mean to tell me that you left the boy with Petunia Evans?"
"Actually it's Petunia Dursley now; she got married to a man named Vernon Dursley a while back," Dumbledore replied, eyes still twinkling merrily, as though he had no comprehension of what he was saying.
"What in the world possessed you to leave the boy with Muggles? And not just Muggles, you had to leave him, Lily's son, with Petunia Evans. I wouldn't trust that woman to take care of a potted plant, much less a child, and yet you thought it was a good idea to leave the Boy-Who-Lived in her 'care?' There are only three people in this world who deserve to be at the mercy of Petunia Evans, and let me assure you none of them are a one-year-old child." By now Snape had worked himself up into a fury, only to be made worse by the fact that Dumbledore seemed as calm as ever.
"Now Severus, I think you're being a little harsh. I realize the two of you might not have gotten along as children, but I would hope we all could leave that behind us. Harry is her nephew, and the same age as her own son Dudley. I was quite sure, given some time, she could grow to love the boy as if he were her own."
Severus snorted in disbelief. "I'm not certain that woman is capable of love." Even if she was, he was certain she wasn't capable of loving anyone with magic. How else could she have turned Lily away?
Dumbledore appeared unimpressed. "Yes, well your disbelief aside there is another, more pressing reason that I choose to leave Harry with his aunt. It was the only way I could be sure that he would be truly safe should Voldemort ever return. Lily died to protect Harry, and her sacrifice allowed me to erect certain very powerful wards to keep him safe. As long as Harry can call a house where his mother's blood dwells home, he will be protected and safe even if Voldemort returns to full power. My chief concern has always been keeping Harry safe." Dumbledore looked straight into Severus's eyes, almost as though imploring, even pleading that the other man understand. Severus swallowed imperceptibly.
"Fine, give me the boy's letter so I can get this over with quickly." Since it was becoming clear that Severus was going to have to visit the home of Petunia Evans and likely explain the entirety of the wizarding world to the Potter brat, he could see nothing to gain by delaying the experience.
"I'm afraid it won't be quite that simple. I'm sure you know the opinions that Petunia held on magic, and, from what Minerva told me when I dropped Harry off, there is little reason to hope that Mr. Dursley will be much better. Since it is entirely possible that they will not want him to come to Hogwarts I need you to make sure Harry gets a chance to make a fully informed decision and that the Dursleys respect the decision he makes. Furthermore, after you drop off his letter this evening I'd like you to stay the night and take him to Diagon Alley tomorrow morning to get his school supplies." Dumbledore was positively joyful as he continued, "It should be a lovely way for young Harry to spend his birthday."
While Severus was grudgingly willing to take the boy his letter, spending the night at the house of Petunia Evans and taking Potter shopping on his birthday decidedly crossed a line. "I don't see why I-"
"Severus," Dumbledore interrupted, the old man's tone having lost the mirth it held only a moment ago. Severus wouldn't have lived so long as a spy by ignoring warning signs as obvious as that, so he slumped almost undetectably in defeat before acquiescing.
"Very well, I shall take the boy… shopping." Severus shuddered at the thought. "But when this goes wrong I want you to remember that I thought it was a bad idea."
"Fair enough," Dumbledore replied, before rummaging through a desk drawer and pulling out what appeared to be two letters and a Gringotts' key. "Here is Harry's letter and the key to his vault; I've been keeping the key safe for him. I'd also like you to take this letter down to Hagrid. I've asked him to go pick up the Stone for me tomorrow-"
"Another bad idea," Severus muttered,
"-plus I believe he made Harry a cake for his birthday, and I'm sure he'll want you to deliver it for him." Since there was clearly no point in arguing with the Headmaster, Severus took the letters and the key before leaving the office to walk down to Hagrid's hut. After as short of a visit as possible, he would go home, get a relaxing dinner in, and finish up the chapter of his book. There was no reason to head out immediately if he was going to be required to stay the night anyway. He would wait until later that evening to fetch Potter from… "Hut-on-the-Rock, The Sea." Oh, just bloody brilliant.