A guy gets reborn into the DC Comics universe as a New God of Apokolips.
He has not read a lot of DC comics so he doesn't know that much about storylines, but has the common knowledge of the more mainstream DC characters as well as some of the more popular storylines.
Starts thousands of years before main DC canon starts.
Might be a nephew of Darkseid or something, not sure yet.
He spends his early life being tortured (aka trained) on Apokolips, but doesn't give up hope that his life will get better. Eventually claims his mantle as a the New God of Hope; Adarian.
Escapes Apokolips and even manages to take some things from Darkseids trophy room (including a green power ring).
The embodiment of Hope, aka Adara, finds him, being drawn to him because of the Hope he exudes, and together they make a blue central power battery and the first blue power ring, making Adarian the first blue lantern.
He takes the database from the green power ring he took from Apokolips and puts it into his own power ring, so that he has general info about the universe (locations of planets and stuff like that).
By the time DC canon timeline starts (Superman landing on earth and so on), the Blue Lantern Corps is already an established organization.
Might recruit some familiar character from DC into his Lantern Corps.
In this story, Blue power rings won't be as nerfed as they are in DC canon, so they wont need to be in the presence of a green power ring in order to be effective.
Let me know what you think, and if you have some ideas on how to improve the concept.
Also, if you want to use this concept, please send me a message first. Would appreciate it.