So I thought to writer down the plot to let you guys see what I was trying to do.

Plot:

A young woman somehow ends up in Steven universe on a empty planet in the past. She discovered she has become a Diamond not just any Diamond the First of gem kind. Getting information from her mind she learned her name is Centenary Diamond. Using the knowledge of the fandom and gem knowledge in her mind she made her first gem a Pearl and name her Pastel.

After making Pastel the Diamond got to work making other gems to discover she can make fandom gems. Example, TMNT, Homestuck, PPG, Undertale ect~. Soon they set to work building the Gem Empire. A billion years later our Diamond is a wise and kind ruler. She made rules for gems kind to make sure no one see others as laster beings. Made gem schools for those who wish to do something different other then what they were made to do. Find a way for gem kind to reproduce just like humans.  Fusion is aloud and normal to see. The gems she made before saw the ones they pop up out the ground with as family or friends. Example Sans and Papyrus or TMNT brothers or camp camp.  Though out the years Centenary learn how to make gems without harming the planet. Doing that time she now owns 26 world's that use to be lifeless. She only goes after lifeless one and fill it with life. Sometime past Sans and Centenary fell in love with each other soon become husband and wife. Some more time passes Pastel is pregnant making her wish for kids of her own. Not sure which way is right to make white diamond give birth or make them from a planet.  She called on her seers to give her an answer they tell their diamond she will have twins a white diamond and a angel aurta quartz. So Centenary and sans do the do.

Time skip

Centenary always has twins one being a diamond and the other being a normal gem like their father but take the same size as their twin diamond. Pastel kids become friends, bodyguards and pearls to Centenary children. They have a childhood.     

(I'm updating the bio so you know what their personalities are like.)

Time skip

Centenary and gem kind are at war with a dark being that destroy anything in it's way.

The mother diamond send her kids off  to her first Borns. White and her twin to keep them safe. She lift both of them in charge of gem kind as her and her husband go off to war. 

(Then I was going to make another book about pink and her twin growing up in homeworld not seeing their parents in years up till pink gets her own planet. After that anther book about Steven meeting his grandparents centenary and sans.)