Lelouch
"He's certainly honest." Lelouch said, a little confused. He was reasonably sure they'd ditched Gary, but he kept popping up. He certainly wouldn't have opened up quite so much if he'd known the technopath was still following them. But what is done is done.
He takes Nunally to the hotel, and books her a room. He's currently loaded, thanks to a few games of chess against aristocrats who should know better, so he makes sure she'll be comfortable, dresses himself in one of the robes they provide to tenants, and then makes his way back to school. It's the furthest he's been from her in six years, but she'll be far safer there.
"Shiki? I want you to go meet a girl named Kallen Kōzuki. Tell her your a black knight, and that I sent you. There's currently a young man attempting to infiltrate our organization using her, I'd appreciate it if you could uncover his identity." He gave a small, self-conscious smile. "You certainly found mine easily enough."
Then he looked at Gary. "Can I trust you?"