A guardian of the multiverse who works in emotion rather than matter, and who named The End aloud when it came.
What he does
He crafts hopeful futures through the dreams of countless beings, and he can read the emotional currents running through a universe "like underground rivers" (ch. 1). In battle his power shows as golden shields.
He taught Zero to strengthen a positive feeling without overriding anybody's will: "Our role is not to control, but to protect the possibility of hope" (ch. 1).
What he saw in Zero
He was the most openly wary of the guardians at the introduction: "Your existence defies categorization. That could be either our greatest asset or our most devastating vulnerability" (ch. 1).
He was right on both counts, in the order he gave them.