>>44288250Because he's Hau's counterpart and both represent an extreme. Both are poles apart that at the end got close and one infects part of his personality to the other, at that's how at the end they both become grey characters.
Gladion not taking everything so seriously and smiling a bit, knowing not everything has to be serious. And Hau knowing not everything is just for fun, sometimes you have to take it seriously.
That's why.