I never really knew Solis. When we were attacked in N-Space, we were rescuing Solis from the dying remains of her TTC when we were attacked by the same entity. Evidently she arrived disparate in time in SL-Space as well, but in the past. She was able to wait until present day, and find Sen and Oolon shortly after they arrived. Together with Drillon, they formed New Gallifrey together.
Because Solis was Castellan and I was an Agent, we deliberately never ran in the same circles. The Castellan must not know of the actions of the Agency – that's the entire point. We did what the Guard couldn't legally do… but what needed done. Sen rarely involved himself in Agency affairs, so it was don't ask don't tell in our relationship. The newly appointed Coordinator – Lord Abbot – was a busy man, and had several assignments for me.
The Abbot was a being of supreme power and unknown origin. He had attacked before, nearly killing David Abbot and taking his remaining incarnations. We knew that The Abbot was a combined TTC and organic being. What we suspected was that he was actually a future version of Lord Abbot's TTC, named Implacable. Somehow, it became combined with it's organic Timelord pilot, but only partially. Missing most of David's consciousness, it was insane – and supremely powerful.
We prepared for its return as best we could. There was a plan to capture it and get information about its origins. The plan was successful, but we had a traitor. Just as The Abbot was contained by the Sisters and examination by the Arcalians was beginning, Olyesti was attacked. Ar had somehow been alerted of our precarious situation, and took advantage. The amount of power needed to contain The Abbot weakened our Barriers, and the city fell quickly.
Soon, our power grid began to fall, and we could no longer contain The Abbot. He escaped, and quickly finishing what Ar started. Bodies littered the ground, regeneration energy causing nearly as much damage as the attacks. But Solis committed the ultimate act of bravery… she collapsed the Eye of Harmony. By hand. The Abbot was a TTC, so still tied to its energy. He was sucked in, Solis established a pocket universe bubble around the Panopticon to protect us all, and then detonated the Eye.
Presumed dead, along with countless others. Our entire planet in ruins. Our Capsules without power. New Gallifrey had fallen.