It's V by far.

She was a shy, kind, and very scared soul. But when she became a disassembly drone, she made a new persona for herself, a psychopath.

V shows that she's a psychopath to hide how afraid that she really is, she's afraid of what she's done and what she's become.

She's hiding how much she is terrified. She's hiding the fact that she is truly the weakest of them, and the most kindhearted, even more than N.

She put up a wall of thorns around herself to hide her fear and soft heart.

She had to push N away... The only person who she loved.