Moviebob, your argument is flawed from the beginning. Hit Girl is getting attention for the over-the-top language she uses and violence she enacts, which can really only work in a bright, GARE-ish movie like Kick-Ass. In the darker, more subtle (kinda) Batman films, I don't think such a character would work in quite the same way as Hit Girl would.
As for Robin in a Batman film, that is a gutsy move. If they're going to put him in a Nolan Batman flick, the biggest thing they have to do is keep Robin his proper age. Don't bring in some 21-year old man who can look Batman in the eye without going on tip-toes in and say "Look! It's Robin!" Keep Robin 11. Keep him a child.
My advice for how Robin would work best would probably earn a lot of hate mail if enacted. I would:
Make Robin an 11 year old child who lost his parents under similar circumstances to Bruce Wayne. However, rather then spending years globetrotting and training to become the best superhero he can be, he just dives right into crime fighting, earning a name for himself.
In the mean time, Batman's alter ego, Wayne, is suffering mentally from his actions in The Dark Knight. Being on the run from the police has made him largely ineffective, as he has no friends on the streets of Gotham. The crooks he hunts all try to kill him, the police are trying to kill him, and even the common folks on the street will try to kill him if they see him. He is torn between the vow he made to his parents to save Gotham, and the realization that Gotham no longer wants him. He begins to debate hanging up the cowl for good.
One night, the night that is supposed to be his last night as Batman, he spies the young vigilante known as Robin getting his ass kicked. At first Batman is in shock over Robin's age, as the criminals defeated by Robin have lied about it in order to save face (no one wants to admit to being beaten up by a pre-teen). However, when it becomes clear that Robin needs Batman's help, he swoops in and saves the day, spiriting Robin away to the Batcave.
When Robin awakes, he finds that his wounds have been treated, but his mask has not been removed. Batman comes down to the cave and tells his story, how his parents were killed and how he too chose to become a vigilante, and how he is now starting to regret his choice. He tries to convince Robin to give up crime fighting, but Robin says that he can't; he made a promise to his parents to fight the evil that took their lives. Shocked by this remarkable similarity, Batman agrees to help Robin in his crusade, though Bruce has still chosen to retire his Batman persona (in the sense that he will no longer go out and fight crime).
He helps him by providing Robin with some of his martial arts training, as well as giving him his own utility belt and gadgets.
In the mean time, whatever villain they've put in the movie has slowly been assembling all
(s)he needs for their masterstroke. Batman has been trying to figure out what the plan is, and finally realizes that the big bad thing is being disguised as some benevolent act, so for him to attempt to stop it would make him even more of a monster in the eyes of Gotham City. This stuns him, and he can't bring himself to stop it. However, Robin is disgusted that Batman can break his promise to his parents so easily, and goes out alone to stop the bad guy. Batman of course realizes that Robin is right and helps him defeat the villain. However, at the last minute, Batman is detained by the big bad while Robin is caught, unmasked, and arrested.
At Robin's trial, Robin is aquitted after lawyers (paid for by Wayne) point out that according to all of Robin's victims, Robin is a man in his late teens or 20s, so this pre-teen can't be the real Robin, only some pretender. However, being so young and an orphan, the court rules that Robin will be a ward of the state, which fills Robin with dread, as he knows that due to the corrupt nature of the Gothom Police will allow them to force Robin into a situation where he can be killed. However, Bruce Wayne comes to Robin's rescue, making him his ward.
Back at Wayne Manor, Robin is wary of Bruce until he meets Alfred, who Robin recognizes from his time in the Batcave. Realizing who really adopted him, Robin asks Batman when he gets to go back out and fight crime. Batman says that "Robin" isn't going to anymore, that he needs a new name, like... "Nightwing".
The film ends with Batman and Nightwing going out into the night to clean up Gotham City.
Now I realize that there are some plot holes, and things that make little sense, and I know comic fans would be pissed that at the end Nightwing would be played by an 11 year old, but I think this would be the best way to work Robin into a Nolan Batman film.
Though he really ought to be in a Superman movie first. Batman has a dog of his own, though...
