Duty, maybe?

[She frowns to herself; this definitely isn't her area of expertise, but she gets it.]

I want to make sure people remember the younger Nier well, too. We weren't from the same world, but he was still important to me. To a lot of people.

[So she understands what Susato means, what she feels she needs to do.]

If anyone's gonna make sure he's remembered that way, and that his work isn't forgotten, it's gotta be you. Nobody could do it like you could.