I've liked the dynamic the two of these characters have. Olette has these natural nother hen like instincts in my opinion. I've always thought she looks after and looks out for her friends because she only wants the best for them. She's the girl who has this heart of gold and she's strong when she needs to be. Olette also reminds me of a person who's the type to cherish and remember the people she meets from day to day. She's generous, loyal, patient, and sweet. Riku on the other hand, while not a complete polar opposite of Olette—thus negating that 'opposites attract' thing—has something in common with her: the care for his friends. Riku cares so much about Sora and Kairi, and he's willing to go to great lengths—he has—to protect and make sure they're alright.
Riku has so much on his shoulders post KH, CoM, and KH2, he's been carrying this burden with him, having attempted to isolate himself because of the guilt that he feels. He's been spending his time since the end of the first game putting pieces back together for Sora. He's done a lot for his friend and why wouldn't he? They've been friends since they were small. The point is this, I've always felt that Riku believes that it's his fault he's dragged Sora and Kairi into this mess; he was the one who's wanted to get off of Destiny Islands and when he did, he made some mis-steps along the way, becoming the 'antagonist' in the first game.
When he and Sora were on that beach toward the home stretch in KH2, he comments on how that world, the world of darkness is perfect for him. He's still beating himself up after the battle has ended, and I thought after some time that not just Sora, but Olette is one to try and show him the brighter side of things, she would be the person who would be waiting for him at the end, to let him know that he's not by himself, and to let him know she'd stick by him. I don't think Olette would judge him for the things he's done, so she would be one to disagree with him when he beats himself up. I think she would consider him a strong and courageous person for doing what he did, and I think she would want to see the Riku that's always been a good person from the start.
Yeah, I know they've never met canonically, but Riku was with DiZ when he created the virtual Twilight Town for Roxas so he could have been exposed to Olette at some point in time, data or not. After all, it was eventually discovered there were two Twilight Towns and Olette was with Hayner and Pence. They were involved, as well; inadvertently, yes, but involved none the less. Olette would get her hands dirty in my opnion and she did, for the sake of helping Sora and I think she would do that for Riku too.
Annnd, I totally have a thing for seeing Riku protect Olette, cause I think he would :3 I like to think they're both stubborn when it comes to protecting their friends and in some random case, each other as well.