Imagine Sawada Nana = Shimura Nana.
Instead of marrying Iemitsu, Nana goes onto become a Pro-Hero, married a nice man with the name Shimura, loses him and gives up her son.
Imagine Tsunayoshi who lost his parents young (but not before his father told him how Tsunayoshi’s grandmother, a Pro-Hero abandoned him). Dame-Tsuna, Dame-Tsuna. No one wants Dame-Tsuna.
But Tsunayoshi always, always thrive under the smallest amount of positive attention. Positive attention that Sensei gladly gives him.
Tsunayoshi who grows up with a smile, gentle hands, and all the charisma a Sky is known for. Kind even. But you should always beware the nice ones. They’re always the ones who run the deepest, burn the brightest. This is a Tsunayoshi who could afford to be kind when he wants to be while calmly and pragmatically plotting how to kill you. (This is a Tsunayoshi in another dimension who was shaped into a Mafia Boss by Reborn).
Then comes Izuku, shattered and broken reflections of each other. Both unwanted by society. Both found by someone who believed in them, someone who gave them the power to shape the world.
The most terrifying thing about Tsuna was not that he could easily sway others to his side, was not the way he smiled and was friendly. No, the most terrifying thing about Tsuna was that Izuku could see him in Tsuna’s place.