Mion and Fion are twin ponies. They are based around Thousand-Year Solo.
They love each other very much, but the course of their lives resulted in Mion staying in her hometown, Ponyville, while Fion ended up in bustling Manehattan. They are separated so far, but hate to be alone. Due to this, you'll find the two using Hoofstep (pony equivalent of Skype) almost daily, talking, laughing, and most importantly, singing the Thousand-Year Solo together. They both know every pitch, note and word, and it makes them feel together again.