He couldn't remember a time when she was not a part of his life. Not surprising; they had met when he was but a toddler. Apparently, his parents had taken him out for a walk, and he had tried to pull on her hair... probably not his proudest moment, but hey, he had been only two years old! For some reason, Homura-nee and his mother had gotten to talking and hit it off almost immediately; never mind that she was a fourteen year old teenage girl and his mother had already been in her... thirties? For a moment he had to think about how old his mother must have been at the time.
Nevertheless, from then on Homura-nee had been his primary (well, his only) babysitter, whenever his parents wanted to go out in the evenings. He only had very vague memories of that time; they would usually play some make-believe game. Looking back, he had to wonder at how patient Homura-nee was with him; he didn't think playing with toddlers would be the activity of choice for a typical teenage girl. But then, he never thought of his honorary sister as a typical teenage girl. There always was something... different about her.
In some capacity, she was always around. Sometimes, he wouldn't see her for days or weeks at a time; but without fail, she would turn up one day and grace him with her sad smile. She also always wore the same red ribbons; he always thought they suited her very well.
He had never met any of her family; once he was a bit older, he had asked his mother about Homura-nee's parents. His mother also didn't know any details, but apparently they were around very rarely; and Homura-nee had lived mostly alone. No doubt that was one reason his mother kept in contact with her at the beginning; she was worried about her living situation.
Sometimes, when she thought no one was paying attention to her, she would look at him with an unreadable expression; he couldn't help but feel that she wasn't actually looking at him, but instead at something (or someone?) that should have been right next to him. Unfortunately for her, he (sometimes) was more observant than people gave him credit for. He didn't know what that was about, and he had never asked her about it; perhaps because at times he felt himself that something (or someone?) was missing from their lives.
Now that he thought about it, while Homura-nee hadn't been around all that much when he grew old enough to not really need a babysitter anymore - she was there for all the important moments of his life. Be it graduating primary school, graduating middle school, the play of the drama club in which he had somehow gotten the lead role. Of course today, his high school graduation ceremony, was no exception.
He happily introduced her to his friends; at least those who hadn't met her yet. It was strange; even though he knew that Homura-nee was supposed to be more than ten years older than him, she didn't really look older than the graduating students. Once she was out of earshot, he even had to put up with being teased that she was his girlfriend! And he had to witness a classmate trying to hit on her as well!
Still, it was a nice ceremony, and he was a bit sad that he would not see his friends every day anymore. But he had already been accepted at the university he wanted, and he was looking forward to university life.
That evening, it was just his parents and Homura-nee; his mother had been able to persuade her to join them at the fancy restaurant where they would be celebrating his high school graduation. It was a nice evening; as always Homura-nee fit right in with the Kaname family, even though she still was somewhat quiet.
Afterwards, at their house, shortly before she left, he managed to ask her one question; he had been wondering about it.
"Homura-nee, is there no one special in your life? You know, while you might not look like it, you're not getting younger!" he teased her.
She did not answer right away; instead she smiled at him for a moment. It was not her usual, somewhat empty smile; no, this was a smile that somehow made her look sadder than he had ever seen her before. "No, Tatsuya, that is not for me."
Then she turned around, and left. It was not a teasing, or exasperated reply like he might have expected. Instead, it was a like an observation, like something about the weather; in her mind, it was just a statement of fact.
"At least, not in this life. Right, Madoka?" Homura-nee whispered to no one in particular, thinking he would not hear her.