Think.
Think about his laugh, how much joy it brings to you when you hear it. When you're upset, you're in your room crying your eyes out. The reason doesn't matter, but you're upset. No matter how hard you try, you can't seem to be happy. So you go to the only thing that seems to make you happy. Mark.
He never fails to make your day, any bad day could be a good one with him in it. But the best part... his laugh.
It's so contagious. You can't sit there and watch him laugh without you laughing yourself. That's one of the best things about him.
It's deep, but not too deep. It lasts long, his laughs. He laughs so hard that he has to catch his breath. It's so great, so lovely.