Since Mikoto showed up, I knew it was a possibility that he would be Leo's partner. Because there's no one else in the story who would fit that role. Before Mikoto, Luft was a possibility, but it was made very clear that Luft already has a partner (likely from another dimension).
It's been a while, so I don't remember all the little details, so forgive me if this doesn't help. So far, there are 3 dimensions involved here. Leo's, Luft's, and Mikoto's. Leo is part of the water dragon tribe and doesn't have a partner yet. Something happened in Luft's world that caused him to be dropped into Leo's world. Leo and Luft spend time together as Luft recovers from his wounds. Then we get a cutaway to Mikoto's world. There seem to be no dragons there at all. We get some little clues that something is being hidden from Mikoto. My guess is that the secret is that Mikoto is not really from that world, but from Leo's.
I also think Luft is originally from Leo's world and migrated to another world to be with his partner. We will have to wait and see if my theories are right.
Omg! Your an angel! The dedication to write so much as a response to my question, I cant help but have my heart flutter there for a moment~. Ok but seriously, thank you. The way you explained it was easy for me to understand and the theories you made are pretty amazing. Again, thank you for taking some time from your day to answer my question, it means a lot.
Yaaaay! They finally meet!