Braig put the finishing touches on his chalkboard drawing, to muffled giggles. "Review time! What is this?"
"A chocobo," Jessie volunteered. "A falling chocobo."
"Who wants to guess what concept this can't-fly-to-save-his-life chocobo represents?"
Watts raised his hand. "Gravitational potential energy converting to kinetic energy?"
"And what's the potential energy equation?"
No one answered. He looked out over a sea of blank teenage faces, and selected one at semi-random. "Squall?"
"Er . . . ." The boy flicked back through his notebook. "Gravitational potential energy equals mass times acceleration due to gravity times height?"
"Exactly so." Braig scrawled the equation next to the diagram of the falling chocobo.
***
Xigbar could, when he chose, see the lines of force in the world as blazing lines and arcs. The models he had once worked with, he now saw writ large: a falling ball crackled with potential energy converting to kinetic energy. He could reach out and tweak, stopping it mid-fall.
The world was a matrix of forces that he could calibrate to suit him.
***
"It's frustrating," Even said, putting down his pen. "I understand why Ansem requires it, but. . . . My samples are ready for genetic analysis, but can I begin my research? No—I have papers to grade."
Braig gave him a one-shoulder shrug. "I dunno. I don't mind. They're good kids."
***
Xigbar kept to the physical; he left manipulations of the mind to Zexion (and to Axel, but he didn't trust Axel). He had once taken pleasure in shaping young minds: but that was Braig, not Xigbar.
(Nonetheless, he found himself showing Roxas the ropes. It was habit, he told himself, nothing more.)
***
"How much more data do you have to input?" Dilan asked, arms folded.
Braig looked up from the keyboard, bleary-eyed. ". . . Twelve pages. 'Cept I forgot the Magnera data . . . ."
Dilan sighed. "You're going to be here all night, aren't you?"
"Sure as hell looks that way." Braig frowned. It was the fifth night in a row—but he did need to start the analyses.
Dilan grunted and vanished, and Braig set a far corner of his mind to thinking of ways to make it up to him as he continued to input the experimental data. But minutes later, Dilan returned, with two cups of foul lab coffee in paper cups, and said, "Give me some of that."
Braig grinned at him and handed over a sheaf of figures.
"Don't thank me," Dilan said, his mouth twitching with the effort of not-smiling. "Clearly I need to help if I want to get some this month."
***
Sometimes, Xigbar thought about trying with Xaldin one more time, just to see if this time anything happened. But it never had, and it never would, and that knowledge ached. He couldn't shake the memory of Dilan, of being Braig, and memory filled his hollow chest with echoes. He felt emptier for remembering wholeness and completion. They lacked an important variable, something vital to this, and to them.
It was better not to think too hard about it—any of it. None of equations came out right anymore, anyway.