Theon is having a bad day. Everything went as well as he expected and in his favor, until today. He didn't expect the change will be caused by would be the first person he got acquainted with during the academy test.
From the day he entered the academy, he made fools of the noble-born students.
He witnessed a few noble-born harassing commoner-born and so he intervened by attacking them mercilessly. They ended up in the hospital but the academy's staff didn't do anything but stood aside.
He came to the capital to exact revenge on the nobles for what they did to him, his home.
From the time he heard about the news, though a bit reluctant to believe in it, the attitudes of the noble to the commoners made him hate nobles very much. In the past, he couldn't vent his anger as there would be repercussions for anything he did.
Now he found a place where there are no such bounds.