He was sitting in his office, awaiting the arrival of Harry Potter. Harry was probably on his way from Minerva's office right now after getting there from Malfoy Manor through the Floo.
Knock. Knock.
That must be him.
"Come on in"
Harry entered the headmaster's office. He greeted him politely, before Dumbledore gestured for him to take a seat.
"First time taking the Floo?" Dumbledore asked, making small talk.
"Yes, sir!" Harry was still looking around the office, mesmerized by all the magical objects in the room.
"How'd you find it?"
"A bit rattling sir." Dumbledore chuckled.
A moment of awkward silence.
"How was your summer vacation, Harry?"
"It was alright, sir."
"I hear you spent it at Malfoy Manor?"
"Yes, I did." Harry said, before quickly adding "most of it…"
"Hmm… So, I take it you and Draco Malfoy are friends?" Dumbeldore asked.
"Yes, sir." Harry said, before reminding Dumbledore "he helped rescue the stone last year."
"He did." Dumbledore said, in a matter-of-fact tone. He then asked, "I'm also assuming you've met Lucius, too?"
Harry simply nodded.
"What did you think of him?" Dumbledore asked.
"Me?" Harry asked, visibly surprised.
Dumbledore nodded.
"He welcomed me into his home, sir." Harry simply stated. A fact. Not an opinion.
"But?" Dumbledore, sensing Harry's reservation, urged him to share more.
"He can be somewhat… prejudiced."
There's more. Dumbledore sensed that, and he sensed Harry's hesitation to share.
"Is there something you wish to tell me?" Dumbledore asked, examining Harry from behind his crescent-shaped glasses.
Harry said nothing for a second, before shaking his head.
"Just be careful, Harry." Dumbledore said. "Not everyone is deserving of your trust."
"I'm aware of that." Harry reassured him, before hesitantly adding "sir?"
"Yes, Harry?" Dumbledore said.
"How do I know I could trust you?" Harry asked.
Dumbledore simply smiled. "You don't."