It was his own grief turned magically to song.

There are much more terrible things than physical injury.

We Slytherins are brave, yes, but not stupid. For instance, given the choice, we will always choose to save our own necks.

Dumbledore paused, and although his voice remained light and calm, and he gave no obvious sign of anger, Harry felt a kind of chill emanating from him and noticed that the Dursleys drew very slightly closer together. “You did not do as I asked. You have never treated Harry as a son. He has known nothing but neglect and often cruelty at your hands. The best that can be said is that he has at least escaped the appalling damage you have inflicted upon the unfortunate boy sitting between you.

And now a chill settled over them where they stood, and Harry heard the rasping breath of the dementors that patrolled the outer trees. They would not affect him now. The fact of his own survival burned inside him, a talisman against them, as though his father's stag kept guardian in his heart.

When I was in my teens I had issues with OCD.

Just because you have the emotional range of a teaspoon doesn't mean we all have.