Some days were harder then others in his opinion. Today was one of those days. Looking around the dark classroom with black curtains over the windows and dark red beanbag chairs sitting around short round tables, the frown on his face just deepened. All the seats were full and here he was at the from to teach these little twerps about the magic of Divination. Today would not be a... pleasant day for them.
"You all expected to come in here and see my crazy face laughing and grinning, like usual, But...," he sighed quietly and looked up down a bit of anger and spite creeping into his voice, "you would be wrong."
Standing up slowly still looking at the floor, he could feel the eyes of the students widen as he talked quietly, "Today you will all close your eyes and try to remember the worst thing that has ever happened to you and when you do, laugh, LAUGH!" He screamed the last word, his head coming up sharply and his eyes wide and frightening.
"Laugh till you can't breath, till you feel your whole body locking up for Air!... Then laugh some more because when you are done, you will feel better then you ever have."
He smiled his maniacal smile at them all and spread his arms wide.
"You will forget it all and every time it comes back, Just Laugh, and you will be fine. Well, as fine as anyone can be who has a reason to laugh like me," At this his smile grew wider if possible and then he started cackling.
His voice started low and long, then slowly got higher till it was ear splitting and fast.
Harry never forgot that lessen. The laugh a mad man that followed his dreams.