Dazai wasn't surprised when the DADA class was about boggarts, as they had been studying it for a while.
Lupin stood in front of everyone asking for silence "As you all know, we are studying boggarts, does anyone know what a boggart is?"
Hermione raises her hand and says "A boggart is a non-being that transforms into the form of the greatest fear of the person who sees it."
"Very good, Granger," says Lupin. "Everyone repeat after me: Riddikulus!"
Everyone in the class repeats the word in a loud voice
"Excellent," says Lupin. "Line up in a straight line. Dazai tried as hard as he could to be one of the last ones, but he fell in fourth place in the line. To have his greatest fear, his weakness revealed in front of so many people who want to kill him
The first in line took a step forward, the boggart turning into... Snape? Neville was afraid of Snape? The teacher had a menacing aura but it wasn't that bad! And with the name of the spell, Snape gained a gorgeous pink flower dress with a lovely flowery hat, making everyone fall into laughter.
Next was Ron, the boggart turned into a spider, which received some nice pairs of skates when the name of the spell was mentioned
Next was a Gryffindor girl, who appeared - it was himself! Wow he didn't think he'd be the greatest fear of someone, but that was good for his reputation, he turned into a... cat? A wrapped-up cat, wow
And then it was his turn, the black mass twisted into himself, a younger version of him, when he was around nine years old. His eyes seemed red with the lighting and his hair wasn't a mess.
He felt glances digging into his back.
"... you're just like him..." the young Dazai said
"He who?"
"The dad... you seem so tired, you look like mommy too..." The boggart approached "Why did you change names? Shuuji was a good name, don't you think, mommy thinks it's a good name-"
"Mommy's dead, and you know that"
Surprise gasps could be heard echoing through the room
"Maybe" the boggart's smile increased "You should be smarter, kill them all and this mission ends... for someone with a 205 IQ, you seem quite dumb!"
More surprised gasps could be heard
The boggart goes into the closet, its red eyes are the last thing visible before the door slams shut with a deafening noise
This might not be good for his reputation