Continuity mistake: When Peter is having his vision of New York, D.L. can be seen picking up Micah and running away. When the camera pans out to show Matt holding them back, D.L. is picking up Micah again.
Continuity mistake: In previous episodes, when we see DL getting into the car as Nikki prepares to shoot him, he pauses for a second and looks around. In this episode, when we see the actual shooting, DL never looks around, he just opens the car door and prepares to get in, without pause.
Chosen answer: It's not been made 100% clear. It was originally assumed that he actually consumed part of the brain, but this has turned out not to be the case. Sylar has been shown all along to have an instinctive knowledge of how things work and how to fix them - this is his actual original power and the ability that made him an exceptional watchmaker and repairer. It appears that he uses a similar process when acquiring new powers - he exposes the brain of the target, allowing him to examine it and determine how their power functions. He can then apply that knowledge to his own brain, allowing him to replicate the ability in question.
Tailkinker ★