It sounds like you're asking about a specific scene or decision involving a character named Robin and why she acted in self-defense. Because the query is a bit fragmented, I’ll cover a couple of common interpretations and invite you to share which context you have in mind. Direct answer

• If Robin cut or hurt someone in self-defense, the typical reasoning is that she believed her own safety or the safety of others was in immediate danger and she used force to prevent harm. The justification hinges on the perception of threat and the belief that there was no safer alternative to stop the danger at that moment.

Contextual possibilities

• In a fictional or dramatic context, “self-defense” often serves to escalate tension or reveal character traits (training, fear, desperation). If the other person was actively harming the team or jeopardizing someone’s safety, Robin’s action could be framed as a protective measure rather than an aggression.
• If the question refers to a specific story, show, or game, the exact motivations can depend on the plot, character relationships, and what precisely triggered the confrontation (e.g., a direct attack, coercion, or an imminent threat to teammates).

What I need to help you precisely

• The exact work or scene you’re referring to (title, episode, chapter, or a brief summary of the situation).
• Whether you’re asking about a moral/ethical interpretation, a plot analysis, or in-universe canon versus fan interpretation.

If you can share a little more detail about the source and the moment you have in mind, a precise explanation can be provided.