It made sense!

For Inara, mostly Jaina at the moment. There are a lot of other people she gets along with or cares about or enjoys spending time with, but Jaina is by far the most significant mutual support for Inara. As I see it, Inara's someone who is completely comfortable drawing other people out and having them confide in her, but who is very, very hesitant to bring her personal problems to other people. She's just barely starting to open up to Jaina in that way, and there isn't anyone else (now that Mal is gone) that she's likely to talk to in the same way.

Mau has a longer list, but the top three are probably Allen, Josh and Cassie. They're his triad of sanity in Aather, Josh and Allen because they kick his ass when he's being crazy and self-destructive, and Cass because he loev her. Mau is kind of terrible at remembering to take care of himself, so he needs people around who are willing to prod him fairly strongly when he does things like fail to eat or sleep. Also he's become more reliant on touch in Aather to provide him with a sense of direction and reality, so being in contact with either of those three keeps him much more grounded than he would be otherwise.

Reverse?