Qinter engaged au where they're engaged to forge a set alliance between the Sandwings and the Icewings (Thorn and Glacier in agreement) and they become best friends and partners on their own accord. Someone started something like this on Wattpad but never continued it. I have ideas, of course... or just scenes that came to mind.
Remember the scene where after they find Hailstorm in WT, they're in the doctor's garden while Kinkajou's getting checked up, Moon's with her, Winter, Hailstorm, and Qibli are alone in the garden? Okay, AU version:
After Winter is traumatized by the necklace, Qibli comforts him like he does in the books, but also hugs and they touch foreheads, just resting there for a little bit. Hailstorm notices this open affection and, after Winter catches him trying to get the necklace back and reprimands him, he clears him throat and asks, somewhat scathingly, "And who is this?" referring to Qibli. Winter then has to awkwardly introduce him like "Oh, this is Qibli, my... um, my fiancé." Hailstorm: "Wait, your WHAT?!". At that moment, Moon comes out to tell them about Kinkajou (her possible future partner), saving Winter from having to answer and leaving Hailstorm in an even deeper mix of confusion and shock.
Instead of the whole dramatic exchange in the books (etc etc ), there's a little bit where they're (W and Q) basically saying "See ya later" and something along the lines of "I mean, it's for our families, right?" in which case they both kinda share a look showing that they've sort of started to want it for themselves too.