At the start, when Toshinori had been injured by All for One and then been told by his sidekick of his fate, he'd simply accepted it. He'd known for years that his life would not be a happy ending for the story books. He'd, perhaps, hopefully, go out with a bang, but he'd known then that any fairy tale he might be taking part in was more like the Original Grimm's tales, all horror and terror and unhappiness.
When Toshinori had decided Izuku would be his successor, he hadn't been looking for anything more than a student to inherit his power, a new vessel of One for All. He hadn't cared about emotional connections, bonds, attachment, no; he'd only worried about making sure the power he carried was not lost with his inevitable death. He'd been selfish enough to wait for someone who struck him as “heroic”, as someone who would carry on his own ideals as well as the duty of One for All, but he hadn't concerned himself with anything more than that.
It's not that Toshinori wanted to run away from responsibility. He'd simply thought that there wasn't much he had to do, much he could do after making sure the intended recipient was turned into an adequate vessel. He, himself, had not had much time with his own predecessor, so he'd thought nothing about living much longer than the pass off.
Izuku was a ray of sunshine in his perpetually cloudy skies, a gentle rain after a long drought, the first flower in a long dead garden. Izuku was the introduction of good things in his life after he'd stifled himself for so long and suddenly Toshinori had a reason to go on. He didn't want Izuku to go through the same thing he himself had, all those years ago. After all, just because Toshinori didn't try to make a connection to the boy, didn't mean Izuku didn't feel one. Feelings could be, and often were, one sided affairs.
It wasn't a particularly special day that it stuck him, this will to live. It had simply been another day of training, of watching a half naked boy run around a trash-heap beach as the Pro hero called out encouragement and admonishments in equal measure, and the sun had been shining brightly, beating down on the two of them. Though it had been cold, the heat of working muscles had slowly seen Izuku strip out of his layers as the day continued. At some point, when Toshinori had been silent for too long, Izuku had turned back to him, as if to check that the elder man was still there, still awake and paying attention, and as soon as Toshinori waved, the boy had smiled.
It had been a full smile, bright and unwavering, and it had suddenly hit Toshinori that this boy meant something to him. More than as the Ninth successor to One for All, Izuku had come to mean hope and faith, comfort and joy and contentment. This teen, hardly more than fifteen, had revived the spirit of heroism in Toshinori, had fanned the flames of hope for a better future, and every day they met together, he found a little bit more happiness in his life. He woke up in the morning, not thinking 'Oh, it's that time again' but something more like 'Oh! Time to meet with Izuku.'
He woke up happy.
Sometimes, his days were hard. He didn't meet up with Izuku all the time, he was a Pro hero and had a busy schedule, and sometimes the villains of the world just didn't stop. Sometimes his old wound pained him, sometimes his mind clouded itself in miseries of could-haves and what-ifs, sometimes he coughed more blood than he could spare and those days were the worst because then he couldn't even help others when he couldn't help himself.
And then a text would chime on his phone, a simple “how are you?” or, more rarely, a personal message of something that struck the boy during the day. Izuku was constantly making his days brighter by simply reminding the man of his existence and it was becoming a necessity of life. Without Izuku's presence, Toshinori's own life became dull and listless.
That day on the beach, when Izuku smiled his bright smile, the sun shining around him and highlighting all the progress the teen had made into building muscles and stamina, Toshinori had paused in the middle of waving back. He'd stared, eyes wide, and realized, quite suddenly, that Izuku was genuinely happy to see him. That Izuku was glad to spend time with him and would seek him out if too much time had passed without a word between them. Izuku had always been a fanboy, certainly, that very first meeting had proved it, but it had suddenly occurred to Toshinori that Izuku was happy to see him in either form, scrawny skeleton man or buff Number One Hero. There was no difference to the teen, both men were his hero, and the naked joy when he saw Toshinori the man was just a real and heartfelt as when he was meeting All Might the Hero.
Izuku was happy to see him, and therefore, he'd be unhappy to not see him again.
It had been like a punch to the gut all over again when he realized what that meant. Right there on that beach, a beaming boy looking to him with faith and joy, and he'd known that he could not leave Izuku alone. He would not follow his master's footsteps, he would not pick the path fate had laid for him. He would live, and live well and long, for this boy and his smile and his heart laid bare to Toshinori in small hands.
At the time, he'd been struck dumb, and that bright smile Izuku gave him had quickly turned into a worried frown when Toshinori stayed paused for too long. The boy had scurried over and invaded Toshinori's space without concern for social norms, and the amount of blood Toshinori had coughed up in surprise at both Izuku's brashness and his own realizations had cut their day short.
It had been hours later, safely at home and curled up on his old, lumpy couch, that Toshinori had finally settled his mind, decisions made and held firm as any promise he'd made before. It wasn't hard to see that Izuku loved him, loved Toshinori his teacher and All Might his hero, in whatever form that love came in, and would mourn him if he died. This wasn't an acceptable thing to allow to happen, and it was time to work against the clock to make it so that it didn't. Maybe he'd have to retire instead of go out in a blaze of glory as he had thought he would, but suddenly, the idea of not being a professional hero wasn't so much terrifying as it was mildly uncomfortable, something new to try and work to his best angle.
The quirkless boy who'd jumped in a villain fight to save his bully, who'd cried at being told that he could be a hero, but still believed and fought against a world set against him, wouldn't suddenly stop following him when he couldn't be All Might any more, and it was as if a pressure had released inside him. Izuku would want him, if not need him, after his usefulness as a hero had passed. Because Izuku, with his heart on his sleeve, loved the man who believed in him, and Toshinori didn't think he was selfless enough to give that up.
He wanted Izuku's attention, in whatever form he could have it, because it was Izuku's attention which reminded Toshinori that he needed to live.
In the months that had followed his renewed will to live, Toshinori found himself watching Izuku more closely. This was the boy he had chosen to pass on his power to, a legacy bigger than either of them. He wanted to know everything about why he had chosen this boy, this brilliant, charming, joyful boy, to carry on such a heavy load.
Izuku seemed to thrive on the attention Toshinori now gave him. Every training sesson at the beach had a more personal touch, whether it be Toshinori getting close enough to pat Izuku on the head, allowing the fanboy to ask questions and write down the answers in his ever present journal, or even occasionally providing a hand made meal for the teen. Often, options 2 and 3 went together, although he noticed that Izuku positively thrilled at touch, yet the boy never initiated it himself. He wasn't sure if it was because of the culture they lived in, or if it was Izuku's own personality that hindered him, but though he never started any touch, the younger would always, without fail, curl into Toshinori's hand, or press close when the Pro hero would stand at his side.
It was an interesting thing to realize; that physical touch, his very presence, would lift Izuku's sprits. It was another sign that he had to continue on, that death had closed it's doors to him, because at this point, he refused to contribute any to the negativity in Izuku's life.
And then Toshinori realized that Izuku wasn't the only one doing better. Each day got easier; every time he laid a hand on Izuku's hair or gently clasped a shoulder, it was like a jolt of energy ran through him. He felt more alive and alert than he had in years, since perhaps that day when All for One ruined him.
He hadn't realized just how much the omen of death had been pulling him down until Izuku unknowingly cast it off of him. Only fifteen, (fifteen and strong, fifteen and righteous, fifteen and full of hope), and Izuku was already a hero to the lead hero of the world. It was a good portent of the future and Toshinori could only look forward with eager eyes.
He wanted to be there to see it, now. And he would. He refused for it to be anything else.
By the time ten months had come and gone, and the UA entrance exam was upon them, Toshinori felt more confident in his choice of successor than he felt of any other decisions in his life. When Izuku screamed his euphoria into the air around the cleared beach, when Toshinori realized just how much the boy had done to prove his capabilities, there was not a doubt in his mind.
This was his successor, this was his legacy, his very reason for living.
And he loved him.
Holding Izuku in his arms, his green eyes closed, his face so full of peace, and his small hand curled right over the man's heart, Toshinori wanted to capture the moment in time, frame it and never let it go. He'd made a commitment to this boy, this child of hope and joy and love for life; he'd promised himself, even if he'd never told Izuku to his face, that above all he would live and live well. He would not go quietly into the night, he would live on until Izuku himself let him go.
As if hearing that promise, the hand over his heart clenched tightly into his jacket fabric and refused to let go. The boy breathed in deep, let it all out, and looked directly into Toshinori's eyes. The man himself only smiled and lifted him closer, until Izuku's forehead touched Toshinori's and they closed their eyes to share breath together. Seconds stretched into eternity and then, finally, Toshinori pulled back, only far enough to press his lips to the sweaty skin of Izuku's forehead.
“Oh darling, my life be yours,” he whispered, and trailed his lips down the side of Izuku's face, until he hovered by the boy's lips. “May I?”
It was, perhaps, the most personal and involved transfer of power One for All had ever had.