Who is the first guardian of Caliborn's session? also, how do we know for sure that caliborn's session has no scratch construct or that a scratch in his session wouldn't change anything? p.s. just wanted to say thank you for the dirty work you guys do here on this blog helping all of us confused fans

First Guardians are assigned to planets, not sessions. A scratch is caused by scratching the construct and sending it up to Skaia to switch the meteors of the Reckoning. Since Caliborn’s Skaia has exploded and he and Calliope were not created via ectobiology and he had no Reckoning, a scratch for his session doesn’t seem possible.