Who is Brendan Lawlor from Give a Boy a Gun and what is their importance?

When Brendan moved to Middletown High School from Springfield in the middle of the ninth grade, he becomes friends with another new student, Emily. Emily says that Brendan talked endlessly about is his old school and how horrible all of the kids are at Middletown, as a result, she distances herself.

Brendan shows numerous signs of being a threat to his classmates in both emails and conversations that he has with Gary and Allison. He talks about who he would like to take revenge on and how he would go about doing it. Other students describe him as having a dark side.