The Cult's leader. Wise, ancient, catastrophically overconfident in his own righteousness.
No one has seen the Remembrancer in person in forty years. He communicates through Sera, through Way-visions, and through messengers who do not know they are messengers. There are three competing theories in the Cult about whether he is one person, a succession of figures sharing a title, or something that has stopped being a person entirely. All three theories have evidence in their favor.
The Remembrancer has the original Ur survey team's findings — or a fragment of them. He knows activating the signal will open the Hantu gate. He believes that what is on the other side is not a threat but a continuation — whatever the Ur left behind on the far side of the gate is the completion of the signal's purpose. He considers the risk acceptable.
He has not told Sera this. He believes she would hesitate, and hesitation would cost them the window.
The Remembrancer is a perfect example of someone who is right about the transcendence and wrong about his right to make this decision for an entire sector. He is the campaign's philosophical antagonist more than its villain. In Act 3, the crew may confront him directly — or deal with Sera's confrontation of him instead, which is arguably more interesting.