This is just a speculation, so don't go jumping the gun just yet. It may contain spoilers, so I suggest you leave this thread right now before you're murdered in your sleep... kidding. ;P Anyways, this what I think the reason for Wheeljack's return and his hunting for Dreadwing: Considering how he's returned without the Wreckers (maybe) and that Dreadwing is here on Earth, I would suspect that he wants to avenge them for what Dreadwing did to them. This is just a hunch, but it would also explain why Wheeljack clashes with Optimus Prime according to the title description a while back. Again, please don't go all gung-ho on me. I'm just guessing.