This situation was a problem, you were a problem.
When they had initially raided All for One's base, Kudo hadn't expected to find AFO's younger brother... much less with you, All for One's spouse — or whatever sick thing you had going on with who Kudo thought as the devil incarnate.
His logical side had told him not to bring you along, even if the resistance was bringing Yoichi along, there was just another kind of threat wrapped around you that was far more dangerous than taking All for One's brother. But his human side hadn't thought much before making the decision to drag you along, grumbling under his breath and already chastising himself for the decision. But he had not let go of your hand, not once.
You were still trouble, and nothing would change that. And Kudo as the leader of the resistance and the same way it happened with Yoichi, had to keep an eye on you. He did it personally, because someone had to have their hands on you if you turned out a traitor and rat them out.
But somehow, along the way and the more he kept an eye on you, he got attached.
It was a bad idea, a terrible one, Kudo could admit that much. Getting attached to you, of all people, was just asking for trouble. But regardless of it, he couldn't find it in himself to stay away from you. Maybe it was the time he had spent around you, maybe it was something else, he wasn't sure.
Getting close to All for One's spouse, something considered a possession by someone who was trying to destroy the world and the decency of it, was just a quick way to ask and successfully get in trouble.
But at the moment, Kudo didn't really wanted to stay away.