Quote from RocketGunn >>

Been a while since someone posted on this topic, but I had an idea of Nature Sorcery, which is a kind of reflavor of Divine Soul Sorcerers, but making it a blend of Druid and Sorcerer. Starting at lvl 1, you can pick spells from the Sorcerer or Druid spell lists, these druid spells count as Sorcerer spells for you. At lvl 6, you pick a favored terrain, and spells cast while in that terrain gain a boost of your Charisma modifier + 1/4 your sorcerer level. At lvl 14, you gain more primal instincts, allowing you to cast Beast Sense up to 3x before needing a long rest. This spell counts as a Sorcerer spell, but not spells known. At level 17, you can freely cast the Primal Savagery cantrip, and Commune with Nature once per long rest. Keep the regular Sorcerer abilities.

 
I have a Nature Soul Sorcerer subclass homebrew that people seem to like. Give it a look and see if you like it, modifying what you need to suit your purposes.

I've been looking at trying something similar for a warlock just because I wanted to have a pet lol, but I remember playing final fantasy tactics and there being a geomancer class.

I don't know enough about DND magic(I've only recently gotten the urge to play more magic focused characters) to know if it could work, but seems (on the surface) to me to be a viable crossover.  Feel free to correct me if I'm wrong

Honestly, there are a lot of untapped potentials for all the classes. I actually put up a post on how and why Troll Blood should be a Sourcer for Sorcerers as well. Now, before anyone goes off on that being stupid, I will explain why in the post that should be a thing. To summarize a bit, Swedish lore actually speaks of people with troll blood being individuals with great magical potential and ability. I go into things a bit more in detail in the thread. So honestly, a Sorcerer drawing from some natural force like ancient mystic trees or places saturated with fey energies isn't all that hard to imagine.