Dumbledore did not say what he regretted.
But Su Er could more or less guess. It was probably because his love had gone unfulfilled. To be honest, back in the Headmaster's Office, Su Er had almost been unable to stop himself from revealing that matter.
In the end, Su Er held back. Ariana wanted to wait a little longer, so they would wait.
He slept well all night.
The next day was the weekend. Early that morning, Su Er was intercepted by Hermione, who had been lingering outside the Hufflepuff Common Room. She did not know what had happened afterward, and her curiosity had tormented her all night.
On their way to the Great Hall, Su Er gave Hermione a brief account of how things had ended.
"So Black is coming next term to be our Professor of Defense Against the Dark Arts? Along with Professor Lupin?" Hermione asked in surprise.
"Yes." Su Er nodded. "You probably didn't know this, did you? Black is Harry's godfather."
"His godfather?" Hermione's almond-shaped eyes widened.
"Shh, don't tell Harry yet. Let it be a surprise." Su Er gave a mischievous chuckle. "He must have been terrified yesterday, right?"
"Thinking his own godfather wanted to kill him."
"He certainly got quite a fright." Hermione nodded. "Actually, Ron was the most frightened. I heard he spent all last night grieving in the dormitory... He thought his Scabbers had heroically sacrificed his life to save him."
Yet Hermione was proven wrong the very next moment. At the Gryffindor table, Ron was animatedly describing his bizarre experiences from the previous night.
"If that's what you mean by grieving." Su Er raised an eyebrow at Hermione.
"I gave him too much credit. I thought he'd at least be sad for a few days over Scabbers, after keeping him