The Lord wanted to know if he had had any success with his mutation attempts as of yet. It was a difficult question. As Ryu had said, this was still very much in the experimental phase. Though he'd had his cart and his minor research, he hadn't had a very sterile environment nor a consistent supply of samples to do anything truly dedicated research projects, yet. There were only the things he could circumstantially note through his small trials. How to spin that into something that sounded enticing, though?
"I've certainly developed a better immunity to it, but I've always had a faster recovery period from illness than most," they began, contemplative. "In my trials, I've seen that the pathogens I've been working on do have a shorter incubation period, and thus a faster lethality, than their natural counterparts. It seems like when fed chakra, these pathogens require less time to make a target significantly ill, at least in the rodent tests I've done. I avoided human studies on the road - I didn't want an infection starting and carrying back here."
That much was somewhat true. He had always had a complicated relationship with his compassion towards other people. The Plague was something he had initiated and he only felt guilty about it occasionally, rarely. To do the same to Takigakure would feel wrong. Even if he had betrayed his village, it was still the closest thing he had ever had to a home.
Then Ryu asked why he was willing to go so far. For this concept, for this research. What had driven him to it. Maybe it was time to be earnest, honest about his past. He doubted he could draw sympathy from it, but being open might still earn him some points.
"I've been interested in disease since I was very young. You are aware, I'm sure, about the fact I was once a prisoner of war in Tsuchi no Kuni." That much had been public record, since he had to be returned.
But he had never, in all his life, told the whole truth about what had happened there. When he told the story as a child, he told the one the scientists had told him to. We were kept in a prison and they treated us well. Mother got sick and died despite them trying to help her.
"They experimented on us. On the children born there. They had me participate in medical trials, infected me with diseases to analyze my recovery timeline. I spent a lot of my childhood sick because of it. It made me curious about viruses and bacteria. They're such simple organisms, but they're also... functionally immortal." Perhaps it's easy to follow the logic from there. Growing up surrounded by death made him very afraid of it. If he could replicate those organisms somehow...