Was Rem's warning fake? Rem warned Light not to hurt Misa or it would kill Light by writing his name in it's Deathnote, but Ryuk had mentioned in the last episode as well as before that either Ryuk would kill Light or that Light would die after living his natural lifespan. As Ryuk has to kill him, was Rem's warning a bluff?

If so, couldn't Light, being a genius, see through his bluff??
Rem warned Light, but later Misa told Rem not to harm him, that she would rather die first. So Rem, in order to preserve Misa's happiness,couldn't kill him.

Light, being a genius, learned how to take advantage of the situation, and used Rem on his plans, manipulating her like any other.