Big Daddy's death. For all its sudden, horrible splash panel goriness.
Not to mention his heartbreaking confession, along with unceremoniously dying without knowing Hit-Girl is alive, unlike the film version.
Big Daddy: I just wanted to give Mindy an exciting life. I didn't want her growing up watching American Idol. I wanted her to be different. Special.
After utterly destroying John G and the rest of his goons, Hit Girl finally breaks down.
Hit Girl: Would you give me a hug? My daddy just died.
Issue 5 of volume 2: Dave's father takes the fall for him for being Kick-Ass and is later murdered in prison. The funeral was what really made this heart-breaking, seeing a brief flashback with him playing with Dave as a child.
Made even more gut-wrenching in the movie because after Mr. Lizewski finds out that Dave is Kick-Ass, Dave coldly tells him that nobody will remember him (his dad) when he's gone. He acknowledges his regret in saying that at the funeral.
Even worse still, Dave’s mother died from an aneurysm when he was fourteen, and his father, having loved her so much, didn’t ever remarry anyone else ever again. Dave is now an orphan.
Earlier, Red Mist SHOOTS A BUNCH OF LITTLE KIDS IN THE FACE. IN BROAD DAYLIGHT.
Not to mention he also raped Katie, right AFTER he shot her father in the head.
Volume 3: Issue 2 shows that Angie Genovese became a social outcast because of Chris's actions in Volume 2. Best exemplified when a relative of one of the people killed in Chris's rampage confronts her for it, condemns her for: "shitting out the anti-Christ" and spits in her face. This gets so bad that she contemplates killing Chris to prevent him from escaping from prison.
Near the end of Issue 2, a guard (later revealed to be Colonel Stripes in disguise) notices Chris watching X-Men: The Animated Series. He questions why Chris would watch that, considering his moral stances. He then casually reveals that he used to adore the X-Men as a child, to the point where he would dress up as Wolverine on a daily basis. It makes you wonder how he turned out the way he did.
Volume 3: Issue 5. The deaths of Insect-Man and Doctor Gravity.
Volume 3: Issue 7. Red-Mist's Redemption Equals Death moment. He reveals the reason why he helped Hit-Girl was because he felt guilty for making his mother a social pariah for his actions. Before he dies, he tells Hit-Girl to apologize to his mother for him and asked her if she forgives him for his horrible acts. Hit-Girl bluntly rebukes him.
The Movie
Might not resonate with some, but when Kick-Ass comes home after a failed night of crime-fighting, he collapses into tears on his bed. While this might be Played for Laughs, it can feel pretty harsh when you think about how genuinely hard this guy is trying to save people, and the resulting feelings of failure. It's a depressing sight.
His narration says it all. Saying Hit Girl and and Big Daddy are the real heroes, "I'm just a stupid dick in a wet suit".
A minor one in the first movie, when Dave approaches Chris at the beginning to invite him over to their table only to be brutally rebuffed by Chris' hulking bodyguard. Although it's played for laughs, the briefly hopeful expression on Chris' face when he sees Dave walking towards him is what lends it tragedy, along with the realization of how many times such a scene must have occurred in the past, resulting in Chris' isolation from other kids his age.
Big Daddy's backstory, especially since unlike the comic, it was true. The fact that he was framed for something he didn't do, was sent to prison for five years, and his wife took her own life as a result of the framing can be painful, especially when comic fans would likely be led to believe that it would later be revealed to be false, only for Marcus (who was mentioned in the backstory) mentions that one of them is still a cop, thus confirming that everything that happened was true.
Damon (directed to Marcus): "I'll tell you who owes her a childhood! FRANK! D'AMICO!!"
The death of Big Daddy. The most impressive thing is that he manages to have both a Moment of Awesome and a Heartwarming Moment right before it happens.
The saddest part is that he can barely speak to his daughter because he's so horribly burned, whispering past his damaged lungs and scorched throat.
Big Daddy:(softly) Good job... I'm so proud of you, baby-doll. Are you okay?
Hit-Girl: ... Uh-huh. But getting shot, Daddy, it hurt a lot more than when you did it.
Big Daddy: That's - cause' I used - low velocity rounds, child. Heh, heh.
Hit-Girl: You're the kindest Daddy in the whole world.
Big Daddy: No, I just... (wheezes) I love you...
Hit-Girl: I love you too, Daddy... I love you too, Daddy. (kisses him) Sleep tight.
Hit-Girl never got to have her hot chocolate with her father...*sniff*
Marcus having to watch Big Daddy get horribly murdered on live internet. He knew it was Damon, so imagine having to watch your best friend getting violently tortured, and then lit on fire.
