HP, Harry Potter, Slughorn, Fifth Year

“Professor Slughorn has meddled with his own recollections.”
“But why would he do that?”
“Because, I think, he is ashamed of what he remembers,” said Dumbledore. “He has tried to rework the memory to show himself in a better light, obliterating those parts which he does not wish me to see. It is, as you will have noticed, very crudely done, and that is all to the good, for it shows that the true memory is still there beneath the alterations. “And so, for the first time, I am giving you homework, Harry. It will be your job to persuade Professor Slughorn to divulge the real memory, which will undoubtedly be our most crucial piece of information of all.”
Harry stared at him. Rowling, J.K. Harry Potter and the Half-Blood Prince (pp. 309-310). Pottermore Publishing. Kindle Edition.

“I’ve got butterbeer, I’ve got wine, I’ve got one last bottle of this oak-matured mead . . . hmm . . . meant to give that to Dumbledore for Christmas . . . ah, well . . .” He shrugged. “He can’t miss what he’s never had! Why don’t we open it now and celebrate Mr. Weasley’s birthday? Nothing like a fine spirit to chase away the pangs of disappointed love. . . .” He chortled again, and Harry joined in. This was the first time he had found himself almost alone with Slughorn since his disastrous first attempt to extract the true memory from him. Perhaps, if he could just keep Slughorn in a good mood . . . perhaps if they got through enough of the oak-matured mead . . . “There you are then,” said Slughorn, handing Harry and Ron a glass of mead each before raising his own. “Well, a very happy birthday, Ralph —” Rowling, J.K. Harry Potter and the Half-Blood Prince (pp. 330-331). Pottermore Publishing. Kindle Edition.

“Ron!” Ron had dropped his glass; he half-rose from his chair and then crumpled, his extremities jerking uncontrollably. Foam was dribbling from his mouth, and his eyes were bulging from their sockets. “Professor!” Harry bellowed. “Do something!”
But Slughorn seemed paralyzed by shock. Ron twitched and choked: His skin was turning blue. “What — but —” spluttered Slughorn.
Harry leapt over a low table and sprinted toward Slughorn’s open potion kit, pulling out jars and pouches, while the terrible sound of Ron’s gargling breath filled the room. Then he found it — the shriveled kidneylike stone Slughorn had taken from him in Potions. He hurtled back to Ron’s side, wrenched open his jaw, and thrust the bezoar into his mouth. Ron gave a great shudder, a rattling gasp, and his body became limp and still. Rowling, J.K. Harry Potter and the Half-Blood Prince (p. 331). Pottermore Publishing. Kindle Edition.

Harry called for the emergency elf to immediately take Ron to the infirmary. Then another elf brought the auror’s to investigate the attempted murder of a staff member. Putting the bottle in stasis for them.

Getting a clean glass and conjuring up water to fill it with, he palmed a few drops of truth serum in it and gave it over to Slughorn to drink. Who gulped it down, followed by the calming draught, which got the truth serum in his system faster. And allowed Harry to get his questions out of the way that both Dumbledore and he wanted. Including just who were Riddle’s friends that he hung out with in school. And who had given him the bottle of Mead to give to Dumbledore.

Abraxas Malfoy was the name of a friend of Riddle, and his grandson had given the bottle to him.

After which, Harry sent him on his way to lie down after his great shock, while he waited for the aurors to arrive.