tl;dr: not even the conductor is immune to the train's threat of healing and growth
... (spoilers ahead. i am on mobile. sorry. i'll make this a color to draw your eye to it)
so it just clicked: one-one's perspectives change after his experiences in book one, not just because of tulip's influence on him-- but rather, likely largely because he got to function as a denizen himself for once
he's got a stark, cold view of denizens as shown in book two. and he had a sterile, irreproachable view of passengers as shown in book four
but then he had to directly function as a denizen, and had to directly interact with and guide a passenger's therapy. he grew from the experiences he gained, and the perspective of having to remember who he is all over again
aside from lake's hijacked pod, and amelia's little speech thing, we really don't get much insight how one-one's treatment of passengers or denizens has changed since returning to his position as conductor. he seems penitent for being vulnerable enough that amelia could usurp him, but also penitent for having done damage
