With the release of the Batman v Superman: Dawn of Justice trailer, we finally feel like we have actually seen Ben Affleck's Batman. But he wasn't the happiest and most care free guy in the world. If you watched the trailer, you see that Bruce is at his breaking point. And it seems that the Joker is the cause of that. There were so many hints in the trailer that I definitely think he will at least make a little appearance. So now, let's get on to the evidence.
The first piece of evidence that we saw in the trailer is this friendly little note that states that Batman was helpless in the amount of Wayne Financial employees that died during the battle in Man of Steel. Which is one of the many reasons that Bruce Wayne is mad.
But that isn't the only reason to make us think that the Joker plays a role in breaking Batman's optimism. As you can see in the following picture, the Joker wrote on one of Batman's old suit, which says: "HAHAHAHA Joke's On You Batman!"
Oh wait...that isn't Batman's old suit...it's Robin's...
That's crazy. And what's worse is that Bruce keeps it around as motivation. Which is another reason that Batman is in a bad mood. And in my opinion, Bruce blames Superman for a lot of what happened, which will help us lead to the ULTIMATE THROWDOWN that we all have been waiting for.
With all of this evidence, I think that I can say that we will see Jared Leto's Joker before Suicide Squad.