The emotional arcs for all of the characters are so beautifully written.

*nods* Yes, and that's another reason why I'm glad I did a seasonal rewatch, because you really can see those developments unfold bit by bit this way.

Re: if Moya had been able to give birth in captivity - given that, as Crais says, that while her offspring can interface with a Pilot he was designed to respond to verbal commands from the Captain directly, I wonder whether Not!Talyn would have gotten a control collar to begin with, or whether the PKs would have concluded that a Leviathan raised by them would absorb their values as a Sebacean child was supposed to.

Also, if Crais had enough clout to remain in charge of the Leviathan hybrid project in an AU where his career doesn't get derailed because of John's accidental crash into his brother's ship, wouldn't Crais then try to get his brother involved into this project as well? (I.e. instead of Crais and Larell, it might have been Bialar and Tauvo.)

Builders: no idea, can't venture a guess.