A/N: Inspired a bit by Matchbox Twenty's "If You're Gone".
Reborn's arrival in Tsuna's life was something that Tsuna would always equate to an extreme form of natural disaster. It was explosive, destructive and outrageous in the volume of disruption it caused, but it proved to be transformative as well. Reborn managed, even from that first meeting, to reshape the landscape of Tsuna's life. Through all of it, from their odd introduction in the morning, to Reborn stealing his bed when it was barely dark outside, something had shifted inside Tsuna, establishing the foundation of what the two of them together, and later so many others as well, would build and hold precious.
Still, being just barely a teenager at the time, Tsuna would always feel that his first impression of madness was a solid one, given that he'd been shot twice in the same day, damaged his school uniform, been made to look like a pervert in front of his school, gotten into a fight and more. While not crippling, either emotionally or physically, the events of the day shook him to his core, and his response in the end was only what could be considered normal. Normal for a teenager, anyway.
"I think you're so mean," he muttered under his breath repeatedly throughout the day and into the night, rubbing various bruises and aches. It would take time for him to learn that Reborn's standard response to anything average or below average in Tsuna's behavior would be a new, and most likely dangerous, challenge. At this moment, however, all Tsuna knew was that he was sore, he was sleeping on the floor and there were booby-traps in his bedroom. He couldn't even begin to imagine what the future would hold for him, or how much a part of it Reborn would become.
"I think we should try." Those words would always shake the boy to his core, even when he'd fully grown and could no longer be considered a boy. They meant that Reborn's keen eyes had spotted some flaw in him that could be corrected with the right obstacle and the right teaching. Something dangerous to Tsuna or his Family that couldn't be allowed to continue as it was. Those words meant another brick laid on that first foundation laid between them; another brick that would be created and laid in place with blood, sweat and tears on Tsuna's part and a firm and guiding hand on Reborn's.
It wasn't until late that first night that Tsuna really evaluated what had occurred throughout the school day, and what Reborn had told him, before his new tutor had fallen asleep on Tsuna's bed. Even Tsuna's inexperienced eyes could see the small changes already taking place within himself, whether he really understood them or not. It hadn't been so bad, confessing to a girl or standing up for himself. Embarrassing, sure, but nothing so horrible that he couldn't survive it and move on. In fact, he'd started to make friends because of all of those risks he'd ended up taking in just in that first day.
"I think I could need this in my life," he muttered to himself on the verge of sleep, completely unaware of the dark eyes watching him intently from his bed. "I think I'm just scared, but is being scared an excuse for hiding from everything?" That was certainly what he'd been doing until now. Shaking his head to clear it, he sighed. "I think too much." It was enough, then, for him to resolve to brush off some of the insanity surrounding him and allow himself to drift off to sleep.
Tsuna would never ask what Reborn saw in him that made him work so hard to teach him and prepare him for what would come. He would question him about his methods, their plans, the various people that they would eventually surround themselves with, but never what convinced Reborn that Tsuna was worth all of the effort and risk. In exchange, Reborn continued to push him, forcing him to grow and evolve, never mentioning to Tsuna that what drove him, even from that first day, was more than just an obligation to fulfill his mission. He would tell others, however, that his determination came from that small spark of acceptance he saw in Tsuna, the willingness to accept his own flaws and try to overcome them.