Sera the Third
Born with the memory of her ‘sister’s’ death she was the most cautious of all. Her own tactics hen dealing with the Martian threat was to build up insurmountable defenses both around the Earth and orbiting their own world. Which worked. She also retired, activating Sera the fourth while roughly in her 50’s. Although even then, she would tinker and ended up making further advancements to the Earth ‘s orbital defense grid. Also there were rumors about her and a welcome drone, but those are neither here nor there.