Difference

"Why are you still helping me? You should feed on my body to survive and get stronger; you shouldn't tell me all these things!" 

"You know, Layton... at first I thought the same thing, but now it's all clearer. If I stayed back here, I could continue to live using a small amount of carbon in your body, and we could both achieve our goal: to reach our final destination. Every time you eat food, I can absorb a part of it to allow my essential vital functions to perform not to compromise any of your internal organs. If we can live together until the end of the journey, we could both get home" the parasite continued, speaking as if the decision to stay in Layton's body was voluntary.

"If what you say is true and we could live peacefully on the Voyager until we reach Freedom... why don't the other Koinobionts think the same way you do?" Layton inquired, trying to reason logically.