He has become very sensitive due to sudden hormonal changes, the insane Daily Prophet, and the public's unfair treatment of him.

Everything in the world is annoying. Lately, even Professor Dumbledore is annoying. He constantly thinks: I'm the one who saved the world, I'm the one who witnessed Voldemort's resurrection, I'm the one who brings home the Quidditch Cup and racks up house points every time, and I'm the one who won the Triwizard Tournament—so why is Ron the prefect and not me?

He can't understand Umbridge, who claims Voldemort is dead while she's terrified just hearing the name.

He hates Draco Malfoy. He always did, but he hates him even more now. He just wants to punch him every time they cross paths.

Whenever he's about to explode from stress, he sends letters to Sirius full of complaints.

He's recently interested in Cho Chang.