Light had finished killing off five of the bad guys when the last two turned to the lower stairs. They were unprepared for this new threat and were easily overwhelmed through the Force. As they were drained of life, Light saw their attacker come up from the stairs. Light swung a saber towards the figure with a single word on his lips, "Sith".
He was prepared to launch further strikes when he saw the face of his adversary. A familiar face, but with the wrong eyes and attitude. Varik usually didn't go around using Dark sided Force powers, and his eyes were blue, last I checked...
He moved back a couple steps, still prepared to battle, but subtly changed to a defensive stance. He had plenty of room to operate, now squarely in the center of the room, as all the furniture had been moved to the sides, making it easier for the fire team to operate.