His absence
Our story starts in the Dumbledore household. The two brothers are so glad to have their sister among the living again thanks to Albus' phoenix, Fawkes. Things seem different between them.
Ariana said, "It's Gelly's absence, Al. I miss him."
Albus muttered, "I miss him too."
Aberforth sighed. "Even I miss him when he might have been the one who murdered you, Ari."
Ariana replied. "I told you to stop blaming him, Abe. I don't blame either of them."
Fawkes added, "Besides, that doesn't matter now that Ari is back among the living again."
Ariana frowned. "Is there any chance that you never really killed him and he's just in hiding, Al?"
Albus stated, "Even if I wanted to, I cannot possibly disclose that to you, Ari."
Ariana shrugged. "Ah, well. It was worth a try. I just miss him, that's all."
Albus put a hand on her shoulder and whispered, "I will see what can be arranged."
Ariana brightened up. "That must mean that you didn't kill him then. Oh, I do hope that we can see him again!"