Crabdad dying in a failed attempt to fight the pirates.
"He's dead, right? He died."
"Ultimately, the hows and whys of Mui's death did not matter. He was gone, and no one would ever even get to know his name."
"He is dead," he repeated, mostly for his own benefit, so he could somehow embrace the notion. "He's dead and gone, and he died in pain, and he lived in pain for as long as I knew him, and everyone else is afraid out there and I'm here. I'm here among Troll Burton houses and puffy clouds while he's gone and dead."
Stillness of Hours
Karkat finding out that a lot of people in the Coalition view him as a tragic hero because he tried so hard to save Mui and failed.