Conversation so far:
What is Haunting Matt Parkman?
Matt Parkman, regretting his actions, is haunted by Sylar.
What does Sylar do to Matt Parkman?
Sylar escalates his tormenting of Parkman, using his own telepathy against him to force Parkman to use his powers to save himself.

Question: How does Parkman react to the haunting?
Self-contained rewrite: How does Parkman react to the haunting?