Vinzent Mayer
She knows she’s treading a line with what she says, but she knows from experience that she would rather say something than 'it’s just a grown up thing, don’t worry about it.' It had only frustrated her, as well as the other children she’d worked with before.
Hopefully Vinzent wouldn’t mind it too much, and seeing the lack of protest, she supposes it went fine enough. For now, the child is content to draw, so she’ll focus her attention on the adult—the one who has the most to gain from this car
Sister listens intently, nodding and with a glance she hopes is non-judgmental. She misunderstands for a moment that Vinzent is still in high school, but she starts to understand the situation the longer he speaks.
Vinzent Mayer When… I see my younger self here. I just… Wish he would have gone through better days as a teenager. Not… Like what I’ve been gone through. It hurts to see yourself, knowing that he’ll get traumatized later on. So much. It hurts to know that your younger self will become most of an empty shell by now.

“…I understand completely.” She had experienced the same thing herself, after all. “It’s like… looking at a happy photograph from your childhood, knowing you can’t return to that moment, to that childish innocence… To know the pain that will become of that child that they can’t possibly imagine…”
Truthfully, she can’t speak from experience on everything. Was she ever innocent? Did she have any happy photographs from her childhood?
Vinzent Mayer "I don’t know what to say to him. Yes, things did get better at some point… But… I’ve hit the worst days before. And memories of these keep coming back, whenever I like it or not. And it usually just.. Is unpleasant. I’m not… I don’t know. I don’t know what to say to him. Especially when it hurts.”

“…..That’s what’s so difficult about this car. Why it’s so difficult to face them. But… It’s not like you have to say anything for the children’s sake. This car is about its passengers—as all of the cars I have seen are at their core.” So she had been in other cars before this one?
“It’s about your own growth. How you choose to face yourself. It’s not like these children are… the real thing. They are not their own existence, they are you… All of you, I mean. What you say to these children… Is ultimately you speaking to yourself.”
Sister laces her fingers together, placing her hands on the table.

“…This car, to me… is ultimately whether or not you can accept yourself and everything that has happened to you in your life. Will you remain trapped looking at a past you can’t change, praying for what could have been, to avert whatever trials that child should face?” This much she could speak from experience. “Or will you be able to move forward, and accept how your past has made you the person you are now? Just as the world moves, as the train moves…”

“…It’s nowhere near as simple as it sounds. Believe me, I… know that much. Especially being senselessly tormented by someone as you have… But it can’t be changed. That child will not grow up to experience that same pain… You are that child, it has already happened… And unfortunately, that cannot change. What I hope you, and everyone in this car is able to do, is to not look at your past selves with regret, and instead think about what comes after… Bad things have happened, yes… But there’s still more left to come. That child’s story, your story, is not over. Think about… your own future. About how you can perhaps find happiness in a way you can face that child and say it will all be worth it in the end.”
The true difference between this woman and Atsuko shines through in this moment. Atsuko, who never for a moment considered anyone unless it had to do with the cold, and Sister, who thought about everyone. It just adds an extra layer of confusion on top of everything else, doesn’t it?