[They need someone to blame, of course. And Chara has to have it be themself. Of course. All the time. It's far, far easier to punish themself than to punish anyone else. It's far easier to hate themself.

Frisk knows that as well as anyone.]

It was something that could have been. Would have been. But wasn't.

Am I to blame for the things my Mirror does?

[Chara made it clear that they weren't, a long time ago. Maybe it wasn't so long ago, but it - hah, it certainly feels it, doesn' it?]

You know how Wonderland works. It reflects things, but it distorts them too. It's a funhouse mirror.

[And here's the punchline:

In this case, it worked.]