people don’t dwell on how crux cared for harrow as much as they should. he was the only one left to attend to her when her parents died, aswell as being her caregiver before they passed.
these are a few examples of him feeling genuine familial affection towards her, because he was all she had. and harrow felt the same
even though crux is a detestable sour old man who swears fealty to the ninth at every juncture, he wasn’t committed to the tomb or to the house of the ninth, he was committed to the reverend daughter of the ninth; his daughter
I think it's important to remember in this context, that Crux may love Harrow, may care deeply for Harrow more than anything, and may be the "only other person invested in her sanity." BUT he still lies to her about Ortus' death on the shuttle. And he's also seemingly killed Gideon multiple times (via hypothermia and a crossbow, though it doesn't seem to stick).
He knows that she's reliant on him for an outside, objective perspective on reality, and he still lies to her. Like all the forms we see love take in these books, it's a terrible kind of love. A love that is controlling, jealous and destructive. He's a lot like John to Harrow in that sense. They both see her as something of a daughter, but they both see "daughter" as a type of possession.
