This isn't about OoP but just something about Percy turning to the dark side.

I'm rereading all the books now, and am on Chamber of Secrets. When Harry, Ron, Hermione and the group go to get their school books, Fred and George happen along Percy reading a book entitled, "Prefects who have gained Power" or something to that effect.

IMO, it's foreshadowing of Percy's ambition and that ambition may be something that Voldemort plays off of. Also, somewhere in this book the comment is made about Voldemort and how he recruited his followers, that he explained that there was no good or evil, merely power and those who had it or were too afraid to take it.

I can see Percy being drawn to Voldemort for the power he desires.

Kitso
KS 361