One interesting plot twist could be that a previously thought - to - be - evil gem actually has a noble reason for their actions. For example, a gem who was fighting against the Crystal Gems might be trying to protect a hidden colony of gems that would be in danger if the war ended a certain way.
One plot twist could be that the pregnancy is not a normal biological one but is caused by some sort of magical or alien influence. Another could be that Steven tries to keep it a secret at first, but then it gets accidentally revealed in a really awkward or dangerous situation.
A plot could involve a half - gem OC who is half Emerald and half Peridot. The OC is discovered by a group of rogue gems who want to use her unique powers for their own gain. She has to escape from them and find her way to the Crystal Gems. Along the way, she discovers that she has the ability to create energy shields like an Emerald and hack into technology like a Peridot. Another idea is a half - gem OC half Topaz and half Bismuth. She is born during a time of peace but when a new war breaks out between Homeworld and the Crystal Gems, she has to decide which side to fight for, as she has qualities from both sides.
One idea could be a gem oc who was created with a unique power that the other gems don't understand. For example, the power to communicate with non - sentient objects. This could lead to all sorts of adventures as the oc tries to figure out how to use this power and the other gems try to figure out if it's a threat or a valuable asset.
One interesting plot twist could be that Steven discovers that he is the one who unknowingly created the time loop in the first place. Maybe his overuse of his powers in a particular situation disrupted the time - space continuum, leading to the loop.
The Diamonds are extremely popular in gem war fanfiction. Their power and their role in starting and perpetuating the war are fascinating to explore. Writers can delve into their motives, their relationships with each other, and how they react to the events of the war, whether it's through changing their views or doubling down on their actions.
A possible plot twist could be that one of the Avengers, say Hulk, is actually a long - lost Gem. His transformation into the Hulk could be related to some dormant Gem power within him. This would completely change the way the other Avengers and the Crystal Gems view him.
One idea could be an OC named Ruby - Quartz. She is half Ruby and half Quartz. Her story could start with her feeling out of place among the full - gem characters. She has the fiery passion of a Ruby but the calm stability of a Quartz. As she tries to find her identity, she meets Steven and the Crystal Gems. They help her understand that being a half - gem doesn't make her any less special. She then uses her unique combination of powers to help save the day during a battle against a new Homeworld threat.
There's a fanfic called 'Male Gem's Adventure'. In this story, the male gem character starts off as an outcast but then discovers his true potential. It has some great action scenes and also delves into the relationships between the male gem and the other well - known characters from Steven Universe. It gives a fresh perspective on the gem universe.
One common theme is self - discovery. Gem OCs often have to figure out who they are in the context of the Steven Universe world. For example, they might be different from the known gem types and have to learn about their own powers and purpose.
A really interesting crossover is when the Gem technology and Naruto's jutsu are combined. For instance, the Gems' ability to teleport could be compared to some space - time ninjutsu. It's fascinating to see how the two different power systems interact.