His recruitment into this battle was last minute. Wolfram & Hart had finally thrown enough money at him to draw up a contract. Nathaniel Grimm was not a gambling man, but he did like his money and his Armani suits. Money and luxury was his weakness and the law firm was thoroughly exploiting it for their own ends. However, thankfully to his guilt ridden mind, it was not a requirement in his contract to kill anyone. Just assist. And. . .deep down, Nathaniel knew that Lilah had been right all along. In all honesty, the assassin was doing this for the challenge.
Teaching high schoolers history and art was only going to get him so far. The challenge lay in the hunt and demise of his targets. The best way to do that? Go for the joints. The joints were the most vulnerable, painful spot on most creatures. They were almost nearly impossible to fully heal and fix. You took out a joint, your opponent was down for the count.
He's already put down a fair few of the Slayer's allies, turning away from his most recent foe to find a man dressed in nearly identical fashion as he was. The "Reaper" as he was called, could exchange his knives for the man's stakes it looked like. Nathaniel eyed the man, cracking his knuckles as he surveyed him.