10 DCEU Revelations From Zack Snyder
3. Darkseid's Involvement
A hot point of contention for a great many fans when it came to Batman v. Superman was Bruce's motivations. For starters, he spends a good chunk of the film killing off lots and lots of people. But he also spends two-thirds of the film foaming at the mouth, attempting to kill Superman. This was a hard pill for many to swallow, as modern iterations of comic Batman have always painted him as a non-killing caped crusader.
But according to a theory posited by a fan which Snyder recently confirmed, there may have been a reason for this. Snyder was asked over social media whether or not Bruce's murderous motives in BvS were a sign that the master manipulator, Darkseid, was actually already inside Bruce's head.
"Darkseid is a master manipulator and can reach into the minds of his enemies to do his bidding. Bruce would've killed Superman and Darkseid would eventually conquer Earth..."
Snyder then liked and confirmed this theory, simply replying that it was "real". So, essentially Snyder is claiming that people were supposed to feel uncomfortable about Batman's actions in Batman v. Superman because it was going to turn out to all be the fault of Darkseid's manipulating of his mind.