For every RP that sees the light of the Internet, there's one that never hatched. Here's a summary of one I was going to do with tau that hasn't got off the ground. It was gonna be an AtLA/FiM fusion (spoilers for both may follow) with the pair of us dividing up a party of ponies. I have codenamed it "Balance and Harmony".
The setting was going to be essentially a fusion between Equestria and AtLA, with no firm decisions made about which geography we were going to use but definitely borrowing more of the culture from the ponies. To make things match up neatly, we decided to incorporate a seapony race (not the early-generation nonsense; non-terrifying ones that look more like this.) Traditionally, seaponies throw waterbenders, pegasi airbenders, unicorns firebenders, and earthponies earthbenders, but crossbreeding can yield other combinations freely; the traits are genetically independent. There is one alicorn at a time and this alicorn is (visually obviously, contra AtLA canon) the Avatar with the power over all four elements.
Separately, there exist the Aspects of Harmony (we re-named the Elements of Harmony so there wouldn't be two unrelated things called "elements" around). As canon, these are kindness, generosity, honesty, laughter, loyalty and magic. In ponies canon Magic is special/central/produces a crown instead of a necklace, but we decided to centralize Kindness instead, because the alicorn/avatar of the party was my instance of Cadence and it seemed correct to both a) give her Kindness and b) give her the crown Aspect. The rest of the party was as follows (paste the codes into the Pony and Accessory boxes to see the designs in the pony dollmaker):
(me as) Blithe Breeze, pegasus airbender bearing Laughter, tentative screenname gales_of (2S2S000010BB76C4FE9E9E00001C44949UN1936001100002K1CE4242FFFFFE2G107F3FCC004CB2, 066CC66066CC66066CC66066CC66066CC6604E8FBAFFFF8C1FFFFFE066CC661FFFFFE066CC66)
(me as) Springtide, unicorn waterbender bearing Honesty (2W2411010021008213004C0200100BB96UN18370040000036100BA95FEDD002D107F3FCC004CB2, 066CC66066CC66066CC666404A66066CC660CC0000191919066CC66066CC66066CC66066CC66)
(tau as) unnamed seapony firebender bearing Loyalty, sibling to Springtide, no designs available because the ponymaker doesn't do seaponies.
(tau as) Geode, earthpony earthbender bearing Generosity (2S2S1I40004F3815FCFE9E0290009FE00UP1837000000001U100A806006EFE2W107F3FCC004CB2, 066CC66066CC66066CC66066CC66066CC6604E8FBAFFFF8C600AA00066CC66503AA00066CC66)
(tau as) unnamed unicorn nonbender bearing Magic.
We had no firm plot, but could easily pick up bits of both canons' arcs, cast Discord as a spirit villain, and do Party Building Plot wherein whoever gets to the Aspects of Harmony first has to find appropriate bearers for the other five. We were not planning to do a "then the Fire Nation attacked" thing; we have a well-integrated friendly population of ponies.
There are no accounts to turn over (only Cadence's has been made, because she is likely to appear when we get around to Clarity Bell in Effulgence, so I'd keep it regardless) but if someone wants to pick this up with me in tau's place, it's available for further development.