4 & 3. Deathstroke and Deadshot
Next up we have the two first confirmed assassins, Deathstroke and Deadshot. We saw the two Ds in the first trailer for Arkham Origins, which showed Batman fighting Deathstroke on the docks before Deadshot attempted to interfere in order to prevent his rival winning the hit money. Respectively being the first and second best assassins in the world, these two will likely go at odds with each other frequently throughout the game, providing a possible basis for the confirmed multiplayer mode (Deathstroke has already been confirmed as playable). Theres little else that can be said about them given the simplicity of their characters, but its possible they might team up later on in the game to tackle Batman at the same time, as thats possibly the only way to incorporate Deadshot into a boss fight given he only attacks from long range.