Well, we all know that Booster was destined to come to our time and that he needed too, atleast according to the Millennium Event.

But lets pretend Booster didn't have to come to the past. What if he and Michelle stayed in the future? Where would he be now? What would be his story?

Personally, I believe this would have happened:

Michael, the day after he originally left for the past, rushes out into the street to save a little girl that is about to be hit by a flying car. Just as he reaches her, he hears a voice: Michael Jon Carter. You have the ability to overcome great fear. Welcome to the GREEN LANTERN CORP.

The ring flies onto his hand, saving Michael and the girl, and Michael begins his journey of redemption as the Earth's new Green Lantern. A year later, Michelle would be made Michael's stand in, making her the second Green Lantern of Earth. And Skeets, donated by the museum to Michael, would become Michael's flying Lantern.

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Author of The Greatest Booster Gold Fan Fic ever written, as proclaimed by members of TV Trope.

While I am not sure that I can agree on that the idea of Michael being selected as a green lantern is "realistic" (but the idea of Skeets becoming his sentinent, flying Lantern is awesome), I've always wanted him to get his hands on a Green Lantern Ring, be it just for a single issue for one simple reason:

To see Hal Jordan going Ape-Sh*t.

And that Booster would be able to at least somewhat handle the ring is not that far fetched. After all the Legion flight rings are controlled by Will-Power as well...and Booster has been shown with the ability to control his ring even from a distance. Something that, if I remember right, is a feat only archiveable by the very strong minded & willed.

I think Micheal would have made his way to Central City and ran across one Eobard Thawne, somehow acquired speed powers in a similar fashion to how Prof. Zoom did and be the 25th century Flash (with goggles sort of like Impulse only using the Blue and Gold color scheme instead of red and white)