Sylar

Petrelli. "What? Peter's father is-- No, you don't believe him, but you could certainly pass for Peter's older brother. Same colouring, eyes, facial structure is more similar to Nathan--" When Mohinder has a conundrum, he sets out on it, trying to puzzle it out loud. "I could do a paternity test. Exceptionally easy. Siblings don't always seem to have the same powers, but complimentary ones... I've never understood why Peter's an ability sponge but his older brother has a relatively tame ability."

And there he is, looking back at Sylar again. Appraisingly.

"You've a complimentary ability. I'll need his blood."