She's known it from the start. Years ago, before the Dark Kingdom, she had known she was simply bad inside, that something despicable lurked within her. The Dark Kingdom only showed her what that was, and set it free to become her face to the world.

Almost, she'd like to tell him: that one cold and cruel act leads to another and another and another so quickly that she's sure there's no redeeming it now, that even she has moments where she knows this has to stop but she has no way of stopping it and can only pray the crash happens soon to finally end it, that the true reason Usagi turns away from her and forgets her is that she can't be saved, that it's the same reason Cloud took back his hand and the same reason no one will ever consider her worth staying for:

She's not. She's a worthless creature of the darkness, and no more.

She doesn't tell him these things. She doesn't tell anyone these things. They lurk in the very back of her mind, rarely faced but always present. These thoughts belong to the girl, and she is the soldier.

"I'm Mercury."

As she speaks those words, some of the introspection melts away and she becomes more sure of herself.

"Whether you call that a monster or not."