Professor Trelawney's Revelation About Snape Eavesdropping on the Prophecy

While walking to Dumbledore's office, Professor Trelawney reminisces about her first meeting with Dumbledore and reveals that Severus Snape overheard part of the prophecy she made during the interview. This shocks Harry, as he realizes it was Snape who relayed the prophecy to Lord Voldemort, indirectly leading to the deaths of Lily and James Potter.