Albus was fairly certain he'd never before been so entirely dominated by a sense of surreal disbelief. He was toying with Gellert's emotions? But in the same instance, his thoughts on the matter bifurcated abruptly, but seamlessly. It was laughable; it was nearly painfully ironic. But it might also have been accurate. Perhaps it wasn't fair, and perhaps it would undermine whatever he thought he was doing, to keep himself and their past so obscured from him.
For a brief moment, the chagrin in his eyes cleared, and his gaze sharpened-- wary and studious. He could not entirely ignore the likelihood that Gellert had designs of his own. Perhaps it was for the best that he couldn't access his own magic; otherwise the temptation, the near-need to pry Gellert's mind open and see for himself may well have overcome his ethical stance on the practice. Blinking, his eyes softened as he tried to sort out whether he was unfairly attempting to hold this Gellert accountable for the offenses in Albus's past.
"We did have something incredible," Albus conceded, maintaining his position pressed back against the desk. "And sometimes I can barely look at you." There was always a concern with telling people of the future, but Albus knew that Gellert had a mind that could handle it, master it, even. If he wanted to. And what Gellert wanted, Albus felt he hardly knew, beyond the obvious. "I loved you, and you led me to believe you cared for me. The plans we made, together, the things we wanted to bring about--" He cut himself off before his voice slid too wistful, too fond, too nostalgic. "You wanted the world, and I would have given it to you." Now, of course, he couldn't help wondering just what sort of new world Gellert would have fashioned from it-- if Gellert's ideals had been real, or if they'd only served to enable achieving his own ends. "But that wasn't enough, it seemed."
Otherwise, why leave? Why leave and never come back? Even if he'd feared British Aurors, surely Gellert was capable enough to avoid them to get in contact with him. And some part of him couldn't understand why he felt as though he was obsessing over this facet, the detail of Gellert's desertion, so exclusively. But Gellert had to know-- especially if Aberforth turned up. True fear welled up over what would happen, should his contemporary brother arrive and cross paths with Gellert.
"I have a younger brother, and the two of you never got on. He didn't like-- he didn't like a lot of things." After a quick breath, he severed himself as much as he could from the emotions clawing up the back of his spine, demanding his attention and his fixation. "An argument escalated to a duel, between the two of you." And he found he couldn't, simply couldn't go into detail while looking at Gellert, while Gellert was so very close. Shutting his eyes, however, proved no help at all. So he moved onto what was significant, his voice both rigid and showing strain with the effort of keeping it so: "By the time it was over, my sister, innocent and defenseless, was dead. And then you were gone."
Gone, with no word, no explanation, no sympathy or remorse. Just gone. As if he'd never been there at all, apart from the shambles he'd left of Albus's life.