You were Jason's twin. Though Jason had essentially left you behind when he became Robin, and you hadn't had a pleasant conversation in nearly four years, especially after you became a villain, you were still pissed off and wanting Jason back. You blamed Bruce. If it weren't for Bruce, Jason never would have left. If it weren't for Bruce, Jason would have never died. So, you tried to attack and kill him. That's how Nightwing- Dick -ended up pulling you away and restraining you, while Bruce made his getaway.

"Listen to me," Dick said, almost as if talking to a child. "Listen, this will not bring Jason back. You think you're the only one that lost him? I lost him to! Killing someone who isn't even responsible won't bring him back."