You see, when I was a wee teenager, I read a lot of novels by Alan Dean Foster (he was the one who wrote the Star Wars novel with canon Luke/Leia. And did the novelization of ST:TAS - you know, the one where they turn into mermaids, and the one where they shrink down to pocket-size, and the one where they're de-aged. He also did a bunch of other media novelizations, and the Spellsinger series, about a grown-up(ish) fantasy world of anthropomorphic animals. You have probably read at least something he wrote if you've read many media novelizations or '80s/90s SF.)
The very first novel he ever published was called The Tar-Aiym Krang. It's the first of a very long series about a plucky space orphan of indeterminate ancestry named Flinx and his telepathic miniature dragon, Pip, who get dragged into various adventures, starting, in this first novel, with Epic Space Archeology.
Anyway, the most important secondary characters in The Tar-Aiym Krang are Truzenzuzex and Bran Tse-Mallory. Bran is a human man; Truzenzuzex is a Thranx, an insectile alien from a race closely allied with humanity. They are both old, erudite, and eminent in their fields; for decades they were sociologists, Tru a Philosophe of the Thranx, Bran a planetary Chancellor with the United Church, until he left the Church under something of a cloud (that nobody *ever* talks about) and they became partners as independent archeologist-adventurers.
They are completely inseparable even when it would serve their interests better to not be immediately recognized as a pair, constantly touching each other, wise, and dryly sardonic, and spend most of the book mentoring Our Hero in a low-key way, being better than you in all possible fields, and playing an endless game of Personality Chess with each other. (Don't ask what Personality Chess is, I don't think anybody but Bran and Tru know the rules.)
I ship them, and will *always* ship them, shipbrothers forever, and the fact that nobody has ever written any fanfic or done any fanart for them and that thranx and humans almost certainly aren't sexually compatible does not matter because it's about emotional compatibility anyway and none of that will ever stop me from shipping them.
Where does Pacific Rim come into this, you ask? Well, we at one point get a backstory flashback to Bran and Tru as young men, when they were shipbrothers together, co-piloting a stingship against the AAnn. I give you nearly the whole flashback here because I can't possibly force myself to cut it down any more.
( Bran at this time suffered his second injury of the action. He sprained a lattisimus, laughing. )
...I think the thing that get to me most about these two is that they had that telepathic connection, that total melding of the minds and unparalleled closeness, but it's tied up fundamentally to their combat experience, and when we meet them later in canon, it's been decades and decades since they've had that connection, and they don't miss it, because they don't need it because they know each other and love each other well enough to know each other's thoughts the old-fashioned way.
So, BASICALLY, I am refusing to care about Pacific Rim and the drift until somebody writes me some Shipbrothers fic. GET ON THAT, FANDOM.
Tru and Bran do show up periodically in minor roles in the later books, but unfortunately Tar-Aiym Krang seems to be the only one where they're major characters. On the plus side, that means all you really need to do to write me Tru/Bran is read Tar-Aiym Krang! Which I have uploaded a v. poor-quality ebook of below, for your reading pleasure.
Tar-Aiym Krang
(Tru and Bran aside, I do really enjoy the Flinx books as good old-fashioned space adventure novels with lots of gratuitous worldbuilding just for the joy of creating something beautiful, and a multi-world Commonwealth where a) Humans don't automatically dominate everything and b) people of European descent don't automatically dominate humanity - I think of all the space opera I've read, Humanx commonwealth may still be the one I find most believable as something that could actually grow out of the present Earth. ...mind you, I have only read about half the books in the series because he keeps writing them and I got way behind in college, so it may start being terrible after about book ten or so, but if you like SF that's about taking some worldbuilding and throwing some tropes at it to see what sticks, they're fun.)