In The Wolves of Mars quest in TTK, the Fallen and Cabal fight each other. They're definitely not allies. https://m.youtube.com/watch?v=ZVS7nbTK6IM And you're right so far. I've made up a lot of stuff, but the Ice Reapers are real. I learned about them on the Destiny wiki. And Bungie said that they will eventually make Europa an explorable area. Since Europa is a frozen world, where else would the "Ice Reapers" be? Most of the Cabal legions are named after the environment they're in. The Sand Eaters, since Mars is a desert, the Dust Giants, again since Mars is a desert, the Skyburners, because of Phobos in the sky above Mars. And the Dreadnaught in the sky above Saturn. As for the Blind Legion and Siege Dancers, they're only different because those legions have specific tasks and operations to complete. As for the Fallen, I already know they're on Europa because there's a concept art of a walker in a blizzard, and the HoW trailer of the captain and the servitor in a blizzard. Old Russia is cold, but the Cosmodrome never had a full scale blizzard. Where else could it be than Europa? Fallen and Cabal are on Europa confirmed. Maybe not in FoG, but definitely some time between now and year 10. And I HIGHLY doubt the house of Dragons will exist, but I just thought it would be more interesting to have a new house instead of just more wolves or something. It spices up the story a bit. The House of Dragons is just a suggestion. Not like Bungie will actually read this, but just in case if they do, I wanted to give them suggestions. That way, if their original plans for FoG are lame, half assed, and need more development, this gives them all of the development they need. I'm not saying It's going to be exactly how I say it is. Again, I'm just offering suggestions. If their plans are already awesome, then I will enjoy it either way. Thanks for your input tho. :)

The Fallen (more specifically the House of Wolves) try to take over Mars after losing their Kell (Skolas) (It's during the 'Wolves of Mars' quest)