(Part 3 of 4 of a series of lore-related posts inspired by the Cataclysm trailer)
With all the fuss lately about Deathwing rising from the cavernous deeps and wrecking Azeroth, we've all been thinking about his titanic, adamantine-plated form and how he towers above the majestic buildings of Stormwind. And we're right to be concerned - as one of the five Dragon Aspects, he's basically a god on Azeroth, and is much, much more than "just" a dragon. The cinematic trailer clearly demonstrates that he is more than capable of shredding Azeroth's mightiest strongholds with his bare claws.
However, we should also remember that he isn't just a big mean dragon. A long time ago, during the Second War, he was more commonly known as Lord Daval Prestor, a highly influential noble in King Terenas' court. More than merely a simple diplomat, Prestor represented the nation of Alterac in Terenas' inner circle of leaders, which included important dignitaries such as Daelin Proudmoore, Thoras Trollbane, and one Genn Greymane, who you may have heard of lately. Terenas trusted Prestor deeply, so much so that he named him ruler of Alterac, and promised him the hand of his daughter in marriage. Prestor eventually disappeared "mysteriously," when Deathwing was forced to flee from the other Dragon Aspects, who had been freed from the curse of the Dragon Soul by Rhonin.
Think about this a bit. Deathwing spent YEARS on this disguise, infiltrating the upper echelon of the Alliance and slowly earning the trust of its most powerful, influential leaders. He is very capable of subterfuge, smooth-talking, and intricate manipulations, something I think we are all overlooking in the wake of his I'M A BIG SCARY INTERNET DRAGON RAWRRR display of power.
In fact, if we look at "Lord Prestor's" actions during the Second War, we can see that he had his claws in every pot - he was involved with the Alliance leadership, he partnered with the Dragonmaw Orcs (the orcs who held his fellow Dragon Aspect Alexstrasza prisoner), manipulated Rhonin into furthering his goals, and attempted to turn the Alliance nations against the Kirin Tor. Deathwing wasn't just playing both sides against each other - he was exploiting everyone. This is an Internet Dragon that knows his trickery.
I think all the bravado and fury we saw from him in the trailer, while genuine, is an act of misdirection, a ruse to make us underestimate him. The Grumpy Elf mentioned how the trailer left a distinct Godzilla or "raging beast" impression. I think this is exactly Deathwing's goal - to make us forget how devious and intelligent he actually is, so we don't discover what he's really up to until it's too late. He's spent years hiding in Deepholm, licking his wounds and plotting...I doubt his master plan is to just rampage across Azeroth like a brainless Gronn. He's got some tricks up his metal-plated, magmatic sleeves, mark my words.