Whenever he had a problem, you'd help him out. Whenever there was an argument, you managed to calm him down from his psychopathic behaviour. This is what had commenced his attachment to you, which enabled his immaturity around you.

You went to the dining hall this morning, greeted by the familiar faces of your classmates... before the whining commenced. Kokichi wailed out his parent nickname for you, crying out crocodile tears, slamming into you before hugging tightly, nuzzling his face into your chest.