This is a repost from the "Ben Affleck IS Batman" thread (irt
this post), because it really belongs here.
I meant i'm worried we wont see Bats do some detective work... I don't know, its just a fear I have.
Okay, I moved this now to Rumors and Speculations. I have pitched the following idea here and also in
this thread in quite a bit of detail. But I'm thinking it very possible that we'll see Batman both being surveiled by the government as a potential threat to Waller's program, and Bats spying on the government in return (Jena Malone's Oracle playing a key role in that). And on this basis, there is reason to conjecture from the following Snyder quote,
"So their relationship is very contentious. What Superman sees as Batman’s limits, Batman sees as Superman trying to control him, acting like an absolute dictator."
that Superman might be setting limits on Batman because the government asks him to (he does in TDRK). And as we know from the first full length trailer, Clark expresses to Perry White that
"This Bat-vigilante's like a one-man reign of terror."
and as Clark tells Bruce to his face at the cocktail party,
"Civil liberties are being trampled upon in your city. People living in fear. He [Batman] thinks he's above the law."
So when we see Clark and Bruce at the party what I'm imagining is that the government (perhaps at Amanda Waller's request) has been spying on Bruce for some time, and knows he is Batman; and the government has asked Superman to reign him in. And Bruce (Batman is always thinking several moves ahead) has already surveiled the government enough to know that Superman is Clark Kent. (This explains why Bruce and Clark seem to know who each other is at the party. It is however the first time they have met out of costume as Bruce and Clark.)
But I'm conjecturing that a deeper layer to this is that this jaded and burnt out Batman has become very bitter toward corruption in government, and sees the military-industrial complex as one of the biggest threats there is to society. (Good Lord, look at what we see of Jesse's Lex in the trailers! The government is giving him access to Kryptonian tech? The military wants to weaponize it so bad that they'll hire a deranged, maniacal psychopath to do that. And look at the results.) He is contemptuous of Superman, perceiving him as younger, green, naive, and a kind of 'lapdog' of the government. Even though in reality Superman probably knows better than to trust the government either--it's an uneasy alliance he has forged with them. But Batman's issues with Superman cooperating with the government would be on the money. For example, for Superman to have left the scout ship in the government's hands is the sort of monumental error in judgment that would fuel Batman's contempt.
Prior to the party scene Batman and Superman may already have had the run-in in which Superman destroys a Batmobile, ripping its doors off for emphasis. There he would be delivering a

message to Batman about his vigilantism. So words would be exchanged here obviously. But the big smackdown between Bats and Supes (Batman 'going to war', as Alfred puts it) comes later.
Anyway... based on this speculation, this scene
precedes this one (and gives it context):
Anyway, the point of this exposition is that Batman's detective work and spying is key.
But what we're actually gonna get in this movie is anyone's guess. I do expect, though, that because Batman is being introduced to the DCEU that he'll get more slightly screen time than Superman.