The Emperor has invited all Senator heirs to the Chrysanthemum. This is because some Senators have been fighting back against him, and he wants to get rid of them and make their heirs the new Senators.
All the Senator's heirs are at a convocation as requested by the Emperor.
"There are traitors and blasphemers from the very highest ranks of this hallowed Empire...Many of you are spawn of these traitors." (pg 158)
Nemesis, who is still disguised as Sidonia, watches in horror as the fortress, which she believes contains Sidonia, is blown up. She was supposed to protect Sidonia, that was her one purpose in life, and now her one purpose is gone.
The Emperor shows the footage of the Impyrean Fortress being blown up.
"No!" (pg 160)
"Sidonia had died, and here I was, here to protect her, to be a sacrifice in her place, and it was all for nothing. I couldn't be alive if Sidonia was dead." (pg 163)
After the death of Sidonia, her one purpose in life, Nemesis must find a new purpose. She makes a deal with Tyrus, and together they are going to take down the Emperor. That is her new purpose, revenge.
Nemesis making a deal with the Emperor's son, Tyrus.