A fanfiction might involve Optimus getting injured in a battle. Ratchet then has to use all his skills to save him. During the recovery process, they have deep conversations about the war, their hopes for the future, and the sacrifices they've made. It could explore their different perspectives as leader and medic.
There could be a fanfiction where Optimus and Ratchet are stranded on an alien planet. They have to work together to survive, find resources, and figure out a way to contact the other Autobots. This would really highlight their survival skills and their ability to cooperate under extreme pressure.
In a fanfiction, Ratchet and Optimus could be sent on a secret mission. They are alone, away from the rest of the Autobots. This gives them a chance to have more personal conversations. They might discuss their hopes for the future of Cybertron, their fears about the Decepticons, and their memories of the old days. The story could show how they support each other not just in battle, but also on an emotional level.
Another idea is for a time - travel fanfiction. Ratchet and Optimus are sent back in time to an important moment in Cybertron's history. They have to be careful not to disrupt the timeline too much while also trying to change certain events to prevent the rise of the Decepticons. This would require them to work together closely, using Ratchet's knowledge of history and Optimus's leadership skills to navigate this dangerous new situation.
One common theme is protection. Since a sparkling is a young and vulnerable Transformer, Ratchet might be in a role of protecting it from various threats in the war - torn Transformer world. Another theme could be mentorship, where Ratchet imparts his knowledge and skills to the sparkling.
Friendship is a common theme. Their relationship as comrades in the Autobot cause often forms the basis of many stories. They support each other in battles and in the day - to - day operations of the Autobot base.
A common theme is the relationship between the OC and Ratchet evolving from a simple acquaintance to a deep emotional bond. Another is the OC helping Ratchet deal with the stress of the war against the Decepticons.
One interesting storyline could be Ratchet and Ironhide having to work together to repair a critically damaged Autobot. They face many challenges during the repair process, like finding rare parts. Their different personalities - Ratchet's more cautious and Ironhide's more brash - lead to some tense but also humorous moments as they try to save their comrade.
Well, there are many Transformers fanfiction websites out there. You can start by looking on Archive of Our Own (AO3). Just search for 'Transformers Ratchet Sparkling' and you'll likely find a bunch of stories. Some might focus on Ratchet's role in the Transformers universe and how a sparkling (a baby Transformer in the lore) might be involved in the story, either through his care or in some sort of adventure plot.