Professor Quirrell took a small step to the left, a step forward, another to the right. He tilted his head with a look of calculation, and then he walked almost directly towards where Harry stood, halted a few paces off with the sense of doom enflamed to the height of bearability.

Nice, Quirrell is tracking Harry by checking in which direction the sense of doom becomes stronger.

I hereby rechristen "the sense of doom" to "the sensor of doom".

Edit: "But what do Muggles know of true power? It is not them who frightens me now. It is you." Typo, should be 'frighten'.

Edit 2: "I could name a dozen examples in Muggle novels of people driven to resurrect their dead friends. The authors of those stories clearly understood exactly how I feel about Hermione. Though you wouldn't have read them, I guess... maybe Orpheus and Eurydice?" -- Aah, what a lost chance to break the fourth wall and cite HPMOR as an example!