Maybe a copout answer since it's MSQ and not personal head canon, but I really feel the bond my character has forged with Alphinaud and Alisaie over the years. We've been through so much together, and we've had some deep talks where they've opened up a lot (despite the WoL not technically speaking, lol). The other scions are more like "trusted allies" whereas the twins feel like my true friends.
Endwalker spoilers:
Is it weird I really, really wish to see Meteion again? I know it would serve no purpose and cheapen the story, but seeing the little starbird fly by at the end of the story gave me hope she's out there somewhere. Also, I would love to be able to go back to Elpis and hang out with Venat, Hythlodaeus, and Emet-Selch some more. Maybe in an alternate life or timeline where thing's aren't, you know... :(