Harry wants answers and is tired of not getting them. So he writes to the only one who might give him those answers. None other then the dark lord. But he gets more then he was hoping for.
Draco drinks a potion that makes him know if a person is lying, and Harry, apparently at fault that Draco is this way, is forced to 'help' him with the effects of the potion. For the first time, they deal with each other with no lies to hide behind.