It could work…
Aquaman. The collectively considered least useful big name member of the Justice League. It’s safe to say that he has been pushed aside (for “good” reasons) in the past few decades, but with the emergence of a Batman and Superman movie and/or a Justice League movie, I think the King of the Ocean has an opportunity to be reinvented for a superhero people can respect again.
Imagine this… Let's say he knows very little about the world outside of the ocean world, except that there are non-merfolk that fight amongst themselves on a regular basis and tend to pollute his kingdom with oil spills, illegal fishing industries, etc. With the continuous pollution (perhaps a new water-born toxin being developed by Lexcorp or some other “evil” industry), his people will begin to question why he takes no action to remedy the problem.
Aquaman should be portrayed, from a leadership standpoint, much like Thor was in the recent films where he is brash, slightly violent, and only having the betterment of his people in his mind when making decisions. The biggest difference between him and Thor’s portrayal will be the absence of a father-figure like Odin. Pretty cool, huh? Everyone fell in love with, at least I did, the recent rendition of Thor and having a DC-version with no leash on him would be spectacular! Because of this free-thinking situation, Aquaman could decide to wage war on the surface world.
He could begin with minor things like making the fish swim deeper to crash the seafood market, then gradually build up to something that is bound to catch the Justice League’s attention…like flooding the world…I know, kind of irrational, frantic, aggressive, but that’s Aquaman (how he could be anyways). So, the League would have to step in to stop this madness form occurring. See how it ties in? Yes? Good.
After the League makes a trip to Atlantis, and much badassery with fighting and “discussion” of a deal, they all reach an agreement to team up as long as the King’s ocean is safe. Also, to ensure Aquaman’s value to the Justice League, his trident (obvious weapon of choice) could be enchanted by Poseidon (thanks to Wonder Woman’s connections with the Gods) to create a controlled amount of water for Aquaman to use. With all of this, there could even be time to throw in a B-level villain/the introduction of an A-level after the team-up…perhaps an investigation of that water-born toxin that began Aquaman’s vendetta against the surface dwellers?
Let me know what you guys think, I’m not an Aquaman enthusiast or anything like that, but I definitely think this could work for today’s audience.