It's a bit far fetched theory but what if the is more to Monkey D. Dragon
Here's my theory Dragon was a Supernova wondering the New world to become PIrate king.
When he met a Noble women who wanted peace,equality and freedom in the world.
She fell in love with the infamous pirate Dragon and then had a child luffy and thus she was executed by other World Government Nobles but dragon was the intime to save luffy.Dragon left infuriated he gave luffy to garp where he would be safe.Leaving his dream to become pirate king he embarked on a journey to challenge and defeat the World Goverment collecting new nakama on the way and keep hiis beloved wifes/girlfriend dream of a world with peace equality and freedom.
Am a beginner so please be nice.