Why is Nathan Schauspielen like Sylar

Nathan is Schauspielen like Sylar cause Nathan IS Sylar. He is probably starting to find his abilities again, and will be back to being Sylar before long.
What does Criss Angel – Jäger der Finsternis have to do with any of this, though?

Well first sylar killed nathan...
but then the mom of both peter and nathan told matt parkman to erase sylar's memories and put nathan's memories instead an because sylar has shapeshifting power, matt turned sylar into nathan petrelli...
so sylar is nathan petrelli for now...
and nathan is dead...
and everybody thinks sylar is nathan, even sylar thinks he is nathan...
so if u didn't see it that's too bad it was the best episode just now :)