The Ship spent a million years alone under the Moon. It will not consider a life without a Lord Captain. When you woke in the dark of it, with a scavenger peeling the hull and a calm voice in your head, it asked whether the two of you should live. You said yes. That was the bond.
You did not arrive with a rank, a marker, or an implant. You arrived from a cave, by way of a button, unconscious for the trip. The Ship asked anyway. Afterward it would not hear of anyone else. Offer the chair to a better astronaut and the question does not parse. The Ship is not angry. It is puzzled, and then it does not move.
You are the Lord Captain. There will not be another. The devotion has the shape of a very old bruise, and the Ship will never explain it to you.