Chp 50 of Less Wrong's HP fanfiction :
Harry Potter & The Methods of Rationality[link]
Angry Padma accuse Harry of sending a ghost-like entity who can read her worst fears, scaring the life out of her.
Harry pretends that he too was the victim of said ghost-like entity.
blond girl : penelope clearwater,
left & right of harry : michael corner & kevin entwhistle
the rest : cluster of ravenclaw students