Tam confronts her maker and says no. Resisting his demand loosens the Nihilist, the self shaped by compleation and the conviction that nothing is worth saving. Even this bleak fragment sees the Echoverse tearing at reality. Its useful insight is one Jace has avoided across many worlds: the solution begins by asking other people for help.
The party is attacked by idealised doubles of themselves and scattered into memory traps. A Detective version of Jace explains the architecture. The rejected selves can re-enter the body, overwhelm the Theorist from within and sever his control, but the Echoverse remains tethered to living flesh. Once the mind is whole enough to choose, the body must still be killed.
Vraska refuses to divide culpability into a good Jace and a disposable monster. Every fragment belongs to the man she loves, including the frightened child, the manipulator and the part willing to overwrite existence. Reintegration is not acquittal. It is the condition under which Jace can finally take responsibility for an ambition no isolated self should be allowed to carry.