Agent Rose is a L.E.A.F. agent that appears in Plants vs. Zombies: Garden Warfare 2. She is housed in a castle, which lies in the scenery behind the Backyard Battleground. While residing in her post, she is unaffected by attacks. If you shoot at her as a zombie, your shots will go right through her.
Agent Rose is invincible and cannot be damaged or vanquished, even if you are playing as a Zombie. This is proven in the second Top Zombie quest, where you are teleported into Agent Rose's castle at one point. If you shoot at her as a zombie, your shots will go right through her, not affecting her.
This could be because it's an NPC and not a real AI.