Thanks for the thread!!
I was ready to click the hell out of the Riku/Mickey option, but then once faced with the poll I realized there are others...
Riku&Mickey is the best relationship/friendship/companionship in the series. [Insert here a 10-page essay that I'm too lazy to type.] My favorite Riku&Mickey moments are CoM, that forest scene in Days, the hug in the sea at the end of KH2, the Symphony of Sorcery scenes in DDD, and all the KH3 scenes where they're together.
This being said, Sora&Riku has to be best duo. "How am I supposed to face everyone?" "Like thiiis" *Sora makes a face* ♡ + I adore their childhood friendship in BBS. It looks so deep and peaceful. And happy. And their team attack is so damn satisfying.
Lea&Kairi made me hope for a new contender on the podium. I hope there's more of them in the future.
I also hope Riku&Kairi become a thing of beauty and badasserie.
The Sora&Kairi fight in Remind...
Xehanort/Eraqus (...)
Not a fan of Isa/Lea//Axel/Saix. Isa/Saix looks like a toxic person to have as a best friend (or boyfriend). They even look dysfunctional as a villain duo / co-conspirators. I'm looking forward to what the next chapters in the series will show us about them, though. Both as adults reconciling and as RG kids in flashbacks.
Actually not a fan of Axel&Roxas as a duo either. I love how their relationship is written, how Axel is caught up in his own Reno struggles and how wanting a friendship with that kid takes him by surprise, but I have to see&play more than the Remind fight to make sure it's all good and wholesome now. Axel f***s up in Days. He is untrustworthy. I'm glad Roxas is mad at him. But I do like their reunion scene in KH3, because so much has happened since then, and I love the shot of the two of them in civilian clothes at the end of KH3. We'll see.
I love Roxas&Xion teaming up on missions, Namine&Roxas, and Namine&Xion. I ship Namine/Xion, so there's that... Their scene together is my favorite in Days. I like Namine's honesty and compassion and Xion working out what she wants to do about her fate. And then they pick up shells together at the end of KH3 and I can't... Let them be awesome friends or more. I want to see that relationship develop.
Riku&Xion as a duo is cringy-interesting.
Same with Riku&Maleficent. Creepy-interesting.
Brain and his Chirithy have matching outfits...
Ven and Roxas complimenting each other during the Re:mind group fight.
The MoM and Luxu -- what is up with this mentor/apprentice relationship. Their dialogues are freaky and hilarious.
Aqua&Cinderella. Aqua teaming up with all the princes, especially Prince Phillip. I LOVED playing a girl in the role of knight in shining armor. Rescuing princesses. Taking Cinderella's hand...
Mini-Ven and Jaq the mouse was pretty awesome, too.
Terra&Cinderella.
Merlin&Cid.
Beast&Sora in KH1.
Aqua&Mickey were fun to play together but they pale next to my brOTP.
Sora&Rapunzel.
Sora&Neku.
Does YX&Sora count as a duo?
...
EDIT: Pooh and Sora. How did I forget that?