A big part of what made Joaquin Phoenix's performance as the titular Joker stand out in an otherwise lame and predictable movie was the significant amount of emotion he put into the character. Phoenix considers himself a bit of a method actor. This means different things to different actors but for Phoenix it apparently means, quote, "There's no fucking way I'm doing a read-through." Robert De Niro, on the other hand, informed director Todd Phillips to tell Phoenix, "Tell him he's an actor and he's got to be there."
His opposition to a read-through (and rehearsing in general) has largely to do with the fact that he thinks acting requires some type of living-in-the-moment anxiety-based instinctual performance. If you're rehearsed, you're eliminating that anxiety, which must somehow make the performance less authentic or less genuine. Yes, Joaquin, please tell that to Laurence Olivier.
At the risk of diminishing the work Phoenix has done (whatever his methods are, they seem to be working), he got really petulant and sorta mumbled through the whole read-through like Micheal Cera on downers. Naturally, De Niro thought that was a load of clownshit and demanded Phoenix talk about it afterward ... except Phoenix faked being sick and tried to duck him. This led to Phillips having to meet with Phoenix separately to urge him to meet with De Niro.
The two managed to figure it out -- apparently De Niro is one of Phoenix's favorite actors, so whatever De Niro told him in their little tete-a-tete must have held some weight. If your movie is ripping-off Taxi Driver and The King of Comedy, it kind of makes sense to listen to the guy that starred in both of those roles. Meanwhile, between this and Jared Leto's Joker, the whole method acting for Batman characters thing reminds us of what the upcoming Batman had to say on the whole subject:
Top Image: Warner Bros. Pictures