"A number of things." The Doctor again adjusted his bow tie defensively. "Medicine, quantum physics, temporal engineering, cheese making..."
He regarded Leto carefully. Plenty of people had asked him that before. But his mind kept turning over why The City would pull him into the world. Maybe it was sick. That was the idea that worried him, that The City was sick and that it called for a doctor.
He would have to keep a close eye on this new world, or everyone trapped inside it, including himself, would be at risk.