I really love the concept of floating islands-- it would make for an interesting map design if the PC had to fly from island to island to explore the whole planet. Avians, in this case being any creature with wings, would be native here. I would imagine that there are a lot of different sub-groups of avians: birds, bats, insects, pegasi, griffins, dragons, wyverns, phoenixes, harpys, perytons, hippogriffs, etc.. Of course, this being TiTs, they would be somewhat human and fall somewhere on the scale of "barely a furry" to "basically bestiality".
Maybe there's a social class issue, where one group is being discriminated against by another group. Steele can choose to fight for equality, fight for enslavement of the discriminated group, fight for enslavement of the group doing the discriminating, or nothing at all. It would be cool if there were different ways the PC could go about doing this-- for example, if the PC has a lot of money and fame, then they could have the option of using their voice to convince the general public/government that this is what should happen. Or if the PC has a high enough libido, then they could seduce everyone and tell the general public/government that they should do this.
I would imagine the cities on the floating islands would be a blend of technology and nature, where homes are made of stone and overgrown plants decorate streets and buildings, but everyone still has access to the newest and most advanced technology. Think Laputa; Castle in the Sky, but better.