Perhaps there could be a plot where Oberon is injured in a battle and Titania has to take care of him. This would be a chance to explore her nurturing side, which might not be as obvious as Oberon's healing abilities. She could use her powers in unexpected ways to help him recover, and in the process, they could have some deep conversations about their pasts, their purposes in the Warframe universe, and their feelings towards each other.
A plot could revolve around a mysterious energy source that is affecting both Oberon and Titania in different ways. Oberon might be trying to contain or study it, while Titania is being drawn to it. As they investigate, they learn more about each other and the secrets of the Warframe world. This would involve a lot of exploration and discovery, as well as some action scenes when they encounter enemies who also want the energy source.
One plot could be a competition between them. They could have a friendly wager on who can complete a certain mission the fastest. This could show off their different skills and abilities in a fun way.
Another idea for the fanfic could be a story set in a post - apocalyptic part of the Warframe world. Oberon and Titania are two of the few remaining Warframes in that area. They have to rely on each other not only for survival but also to try and rebuild what has been lost. Titania could use her nature - based powers to start to regrow plants and bring some life back to the desolate land, while Oberon protects her from the remaining hostile forces.
A possible plot could be that Oberon and Trinity are sent on a secret mission to infiltrate a hidden Grineer base. Oberon uses his abilities to create distractions while Trinity sneaks in to retrieve some important data. They then have to fight their way out together, relying on each other's combat skills.
There could be a fanfiction where Oberon and Trinity team up for a mission on a desolate planet. Maybe they have to face a new and powerful enemy faction. Oberon's nature - based powers and Trinity's healing and energy - based abilities would make for an interesting combination. They could start off as just comrades in arms, but as the story progresses, a deeper bond of friendship might develop between them.
One interesting story could be about an operator who forms a deep bond with their Warframe during a difficult mission. The operator discovers new abilities of the Warframe that were previously unknown, and together they overcome a powerful enemy. For example, the operator might find that their Rhino Warframe can perform a special charge move in a particular situation that saves them from a horde of enemies.
A lot of Warframe fanfics explore the backstories of the Warframes themselves. Like a fanfic that delves into the creation of Excalibur. It could tell the story of how the Orokin designed him, what his original purpose was, and how he evolved over time.
One common theme could be the exploration of their relationship dynamics. Since it's a fanfic, the writers might focus on how they interact, whether it's a love - hate relationship or a slow - burn romance.
I'm not sure exactly which Oberon x Lemon fanfic is available. You could try searching on fanfic platforms like Archive of Our Own. They have a large collection of various fanfictions, and you might be able to find some Oberon x Lemon ones there.
One interesting plot could be Goku and 17 teaming up against a new, powerful enemy that neither could defeat alone. They combine their skills and powers in unique ways.
One interesting plot could be Sasuke taking Boruto on a special training journey across different hidden villages. This would not only strengthen Boruto's skills but also give them a chance to bond like master and apprentice.
One interesting plot could be two Pikachus from different regions meeting and learning about each other's unique electric attacks. For example, one Pikachu might know a special move that the other has never seen before. They could then teach each other and become stronger together.