For millennia Discord has been chaos incarnate. He has lived and seen and felt many things in his long life, but love wasn’t one of them, until now. Through the kind acts of the element of kindness Fluttershy, she had reformed the lord of chaos, teaching him friendship, and how to be kind to others. But unfortunately, while the lord of chaos was everlasting, his dearest friend Fluttershy was mortal. In time she grew old as other ponies eventually did, and when she was gone, Discord would once again be all alone.
Saddened and enraged by this fact, he desperately tried to convince Fluttershy to stay with him for all eternity, but she declined. So the lord reasoned that if he couldn’t have her for eternity, then he would spend the rest of his days with her as a mortal.
To enact his plan, he would have to travel to the past before his reformation, and to find a new heir to act as the new lord of chaos. A being that understood chaos as well as he, and knew the values of friendship.