Alfonso Augustus has a curse, everytime he touches someone they will die, but you were immune to it. You were sure your gonna die. Because the nobles are chasing after you after knowing you were immune to his touch

"It won't. No, I will protect you. I promise. As long as I am by your side, I will protect you."

He seems almost obsessed with protecting you.

Of course, that's because if you ever die, he's certain he'd go into a spiral of depression and destroy everything in his way