Relationship meme me?

Tobias is probably one of the teammates Josh is closest to at this point, other than Joy. Part of that is that he's actually able to help him out in various ways; the rest of TE either doesn't seem to need it, doesn't seem to want it (to the point of actively shutting him out in one case) or is beyond his ability to help. So he feels like he's actually contributing to the relationship, which is something he generally kind of needs, but it's also not one-sided; he trusts Tobias, too, and would be comfortable talking personal things out with him.

Reverse?

Relationship meme me?

At this point Joy is definitely the teammate Josh trusts and relies on the most; he's very comfortable with her and thinks of her as a good friend. It helps that she's closest to the TE he more-or-less grew up with -- more reasonable, more prone to thinking and talking her way through things -- of all the current game-playing teammates. He feels better knowing she's around, and trusts her to herd the newer game-playing TEs when needed.

Reverse?

In some ways, Josh is kind of the 'wise mentor' when it comes to Aather, in that he was one of the few people still around from Joy's introduction (the other being Kitsunebi, whose age and general inexperience with humans makes it hard to for Joy to consider him a mentor). It's a bit more even both as Joy recovers more memories* and gains direct experience with Aather.

Sell me on Josh's canon?

* The seasonal countries really gives Joy ideas about Aather.