Big Sisters, Letting it All Go, and The Luncheon: To Spoil Anna (that last one also has a yuri-esque theme to it as well.)
They're certainly not complicated, but if you are looking for a quick read and you really liked Frozen, you're in luck.
My favorite cartoon, and arguably my biggest transformation influence, is Shrek, which hardly needs fanfiction. I think it already is what we would wish it to be.