Darkness. No Parents.
And with those three little words Batman managed to steal The Lego Movie and get his own standalone spin-off, in theaters now. This almost didn't happen.
According to Looper, Lego Movie directors Chris Lord and Phil Miller's originally planned to have R2-D2 be a member of Emmet and Wyldestyle's team, not Batman. This is not entirely surprising since Lord and Miller didn't return to direct The Lego Batman Movie because they are currently busy prepping a Han Solo prequel for LucasFilms. Plus, they still managed to work Han Solo, Chewbacca, C-3PO and Lando Calrissian cameos into The Lego Movie. However, the original plan called for R2-D2 to have a sizable role as a comic relief sidekick. When LucasFilms said no, worried as they were at the time about their pending sale to Disney, it created an opening in the story for Batman.
There's still a part about this which doesn't make sense. It's actually crucial to the plot of The Lego Movie that Wyldestyle has a super cool boyfriend who instantly causes Emmet to feel inferior, and who wouldn't feel inferior compared to Batman? But if R2-D2's absence freed up the screen time which went to Batman then who exactly would have been Wyldestyle's boyfriend if R2-D2 had been around? This guy:
That's Metal Beard the pirate, voiced in the movie by Nick Offerman. The idea was for Wyldestyle to have the coolest boyfriend imaginable, and Metal Beard seemed to fit the bill, standing up to Lord Business earlier in the story, forced to rebuild his own body from scratch and commanding his own ship which he uses to rescue Emmet and Wyldestyle. All of these plot points still made it into the film; they just took out the part where Metal Beard was Wyldestyle's boyfriend. Instead, that honor went to Batman, and now we have a Batman Lego Movie. To think, we could have had a Metal Beard Lego Movie.
Scratch that. That probably never would have happened because while Metal Beard's perfectly fine he's no Batman.