A one time thank you for saving his life a couple episodes earlier?Now, didn't technically FIsk kill his wife? He was deflecting the object meant to kill him, but in his fury, didn't see how the impact would have killed his wife.
I thought Bullseye was thrown off his game by Matt, so that was why Fisk had a chance to defend himself.
I don't exactly have a handle why Matt would want to to protect Bullseye?