DISCLAIMER I don't own any thing
Meta Knight is Nightmare's failed creation for betraying him when MK was 14. (All MK did was refuse to listen and stab Nightmare's finger...).
Afterwards Meta Knight started to look for people willing to start a war. Soon after Meta Knight became the last star warrior. (Until episodes 99 & 100 from the tv shows).
Meta Knight along with his two followers Sword & Blade came to Planet Popstar in search of a new generation to take Nightmare down. In order to get what MK needs, he offered to become the asshole King Dedede's personal guards/knights.
After the long suffering of the asshole's every stupid ass wish, MK and his followers finally got what they flipping needed. A starship crashed in Dreamland like Kabu predicted and a small puffball/kirby (I don't care what you flipping call it XD) named Kirby appeared. Kirby was this new generation (apart from the the others like Knuckle Joe).
Kirby was to be trained and prepared to finish Nightmare for good. Weird thing is that MK knew alot about Kirby even before he knew Kirby (reason why I think MK is Kirby's father). Finally came time to defeat Nightmare, so Meta Knight got his battleship Halberd to fly himself and many others to Nightmare's location forthe final battle.
Soon after Nightmare's sorry defeat, everyone pitched in to rebuild Dreamland and yes even MK. So this is MK's story and I hope you enjoyed it and if not then screw you.
This was made all from memory so now my head hurts like hell. :-p