Near the end of the flashback Pyren steps into the library when Serinth is out mingling and starts going through her memoirs. But to his horror the books, all of them, thousands at this point, are all descriptions of the various ways the pack dies, as well as other odd notes like "Moose did not spawn, revert."
He keeps flipping through the pages, pulling one book out after another, and it's all the same: the group dying again and again in horrible ways, mostly in the Deadwood.
He turns around to discover she's entered the library and spotted him, and she begins to grin and laugh manically. She explains how excited she is to see him, that she's been waiting for so long to show him this, that it's these little blips in the sea of endless repetition that prove she's still making progress.
She gestures to the library and says this is her real legacy, not the he war victories or what came after, this. She explains that in fact she's been doing it for so long that she dosen't actually remember how it started. So it's quite possible that there was a library before this, that she's been doing this since the beginning of the time. She asks Pyren doesn't that feel like a fitting punishment for her sins?
But Pyren is terrified and he doesn't understand, she's seen them die?
She smiles and touches him sweetly and explains that sometimes she's the one who kills him.
Then she tries to fuck him but he jumps away and runs out the door, but she hears him laughing as he runs and stops to turn to her as she tells him that she knows his story too.
He bolts out and runs into Jagex, who asks what the fuck is wrong with him, and but he runs off away from the house. This is the same scene that we see in Jagex's flashback from his perspective, and then in that scene Serinth comes out immediately after and Jagex asks her what she did to him. She plays it off (still smirking, still excited to be making progress) saying "Who knows?" and then changes the subject.