One Detail In Half-Blood Prince Ruins All That Was Left of Professor Slughorn's Dignity

Initially, he's just a tired old man, as he claims himself, who just wants some peace. Being on the run from the Death Eaters only adds to the initial impression.

But as we're getting more acquainted with Slughorn — when he returns as Professor Slughorn, of course — it becomes apparent that he's very flawed, to say the least.

We don't think many people would call him a bad person, but it's impossible to deny his ignorance, nepotism, elitism, and cowardness. And boy do we have something to tell you about Horace's cowardness.

There's a tiny detail in The Half-Blood Prince that allows us to understand just how cowardly Slughorn truly was. As Reddit user magic8ballzz pointed out, this here line from the book uncovers quite a lot about Horace:

"Slughorn's eyes lingered for a moment on the ring too, and Harry saw a tiny frown momentarily crease his wide forehead."

This happened during the meeting between Harry, Slughorn, and Dumbledore when the latter was trying to convince the potion master to come back to Hogwarts as a teacher. What's so peculiar about this line, you may think?

Horace Slughorn was young Tom Riddle's favorite professor and the one who told him about Horcruxes. During his last two years as a student, Riddle was already wearing Marvolo Gaunt's ring, and Slughorn was sure to have seen it multiple times.

As we all know, Tom Riddle later became Lord Voldemort, and Slughorn was aware of it. He also knew about his student's interest in creating Horcruxes.

When Slughorn saw that very same ring on Dumbledore's charred hand and noticed the crack in the stone, he must have put the pieces of the puzzle together.

Voldemort has somehow returned from behind the Veil. Voldemort wanted to create Horcruxes which allow just that. Voldemort was in possession of this exact ring when he learned how to make a Horcrux.

Dumbledore now has the ring which obviously cursed him, and the stone was severely damaged.

It's pretty safe to say that Slughorn realized everything the moment he saw the Gaunt's ring on Dumbledore's hand: he was many things but never an idiot.

But he didn't share this information. Even more: after this meeting, he altered his memory about telling young Voldemort about Horcruxes.

Horace Slughorn knew at that point that this information was crucial to bringing Voldemort down but he decided to cover it up out of selfishness and cowardness. It was Slughorn's conscious choice.

And there goes his sweet fish bowl story from the movies.