Warning: Contains SPOILERS for The Batman.
Robert Pattinson's Batman injects himself with a mystery green substance in The Batman, with a couple of possibilities as to what it actually is. The Batman's version of the Dark Knight is different to any before, in particular with how brutal he is. Pattinson's take on the character doesn't kill, but he does give himself over to his inner-rage and violent urges, only stopping himself in the final moments, pushing himself close to the edge on several occasions. That's no more evident than in The Batman's ending, when he takes down a Riddler goon and almost loses control.
The moment comes when Batman has nearly been defeated by the Riddler's army, but it's aided by a substance of some kind. Fading fast and with Catwoman (Zoe Kravitz) in danger, Batman pulls out a syringe and injects himself with what looks like a green serum. The impact is instantaneous, with a revived Batman beating the Riddler goon (who is revealed to be the same guy he speaks to at the funeral earlier in the movie) to within an inch of his life, only stopped by those closest to him.
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The Batman never explains what liquid Pattinson's Bruce Wayne injects himself with, despite showing such startling effects. It's the first and only time he uses the substance in the movie, suggesting that it's something he has developed for such life-threatening, last-ditch emergencies, which also further implies how dangerous the green serum really is. It's possible, of course, that Batman injects himself with adrenaline or something similar, giving him that rush of energy, power, and rage that allows him to fight the Riddler goon and almost spin out of control.
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