Skull isn't actually sure how it happens.
He just sort of…gets pulled in.
The kid is ridiculously magnetizing. He pulls people in. He doesn't ask them to change for him, but he brings out the best in them.
Makes them want to change. Want to be better.
Tsuna is like light in the darkness. A sign of hope, and comfort. Something that anyone who spends a significant amount of time in the dark will cling to and shield to the best of their abilities.
A bright shining light that has stepped into one of the darkest places in the world- the Mafia.
He's pulling in the strongest people in the world and he doesn't even realize it.
Skull supposes that is why the pull is so strong on the most powerful of them. They're used to people trying to pull them in for their own gain, but Tsuna…
Tsuna doesn't do that- isn't even aware he's doing it. He just genuinely wants them all to be happy and safe.
His smirk is soft and fond along the edges.
Foolish kid.
Skull would watch out for him though. Even if he hadn't been Giotto's many greats grandson Skull would have watched out for a kid this light and welcoming.