I'd recommend 'City at War' in the bayverse tmnt fanfic world. It has a great plot that really gets into the action and relationships between the turtles. It's exciting from the start and gives a good sense of the bayverse setting.
One great story could be 'Optimus' Redemption' which delves into Optimus Prime's internal struggle in the Bayverse. It shows his journey to regain his true self after facing numerous challenges. Another is 'Bumblebee's New Adventure' where Bumblebee embarks on a mission to save a small town from a new Decepticon threat. And there's also 'The Bayverse Alliance' which focuses on the combined efforts of the Autobots and humans to face a greater evil.
Archive of Our Own (AO3) is also a great place. There are some really high - quality bayverse tmnt fanfics there. The tagging system makes it easy to find exactly what you're looking for. You can search for specific genres, pairings, or story elements related to bayverse tmnt.
Well, for a 'transformers bayverse crossover fanfic', you could have Ironhide as a main character. He's tough and a great fighter, which would be useful in the often - dangerous situations in a crossover. From the Bayverse, a young scientist or inventor could be a main character. They could bring a fresh perspective and new ideas to the table when it comes to interacting with the Transformers. Also, Starscream could be a main character. His ambition and treachery would add a lot of twists and turns to the story, constantly causing problems for both the Transformers and the Bayverse characters.
One idea could be having the Autobots and Decepticons end up in the Bayverse's version of Chicago during a major crisis. They could team up with the local military forces there to fight a common enemy, like an alien invasion that is different from their own Cybertronian battles. Another idea is to have a human character from the Bayverse accidentally stumble upon a hidden Cybertronian relic that has the power to transform Earth's technology in unexpected ways, leading to a race between the Transformers and various human factions to control it.
Another interesting one is 'Rise of the Bayverse OC'. In this story, the OC starts as a small - time mechanic who accidentally gets involved with the Transformers. The fanfiction gradually builds up the character's importance in the Bayverse world. It shows how the OC uses their human knowledge and skills to help the Autobots in their fight against the Decepticons. There are also some really cool scenes where the OC modifies some of the Autobots' equipment.
One key element is the relationship dynamics. Since it's Bayverse, the relationships between Autobots and Decepticons, as well as between the Transformers and humans, are crucial. In terms of the 'lemon' part, it should be written in a way that doesn't seem forced. Also, the world - building should be consistent with the Bayverse, like the look and feel of the Transformers' world, their technology, and how they interact with Earth. For example, if a story involves a Transformer falling in love with a human, how does that work in the context of their different anatomies and cultures? That's an important aspect to look for.
One common trait is courage. Male OCs often face the powerful Decepticons without flinching. For example, they might stand up to Megatron when no one else would. Another trait is loyalty. They are usually loyal to the Autobots and their cause, helping them in their fight for Earth.
You can start by looking on fanfiction websites like Archive of Our Own (AO3). There are often a ton of fanfictions related to Transformers Bayverse. Just use the search function and type in 'Transformers Bayverse Sparkling' and you'll get a list of relevant stories. Another place could be FanFiction.net, though the quality can vary more there.
The appeal lies in the fact that it combines two elements that fans love. The Bayverse has a large following because of its big - screen action and modern take on the Transformers. The 'Sparkling' idea adds an element of cuteness and new beginnings. Fanfiction writers can then take these elements and create stories that range from heart - warming to action - packed, with different pairings and plotlines that keep readers hooked.