Maybe a new character could be introduced as the main antagonist. This character could be jealous of Sonic's friendship with Cream and Bokkun. So, they try to drive a wedge between them by causing misunderstandings and getting Bokkun to play more harmful pranks than usual.
Perhaps the fanfiction could center around a race. Sonic, of course, loves to race. Cream wants to prove herself as a fast runner too. Bokkun, seeing an opportunity for chaos, creates some obstacles during the race. But in the end, it leads to Cream and Sonic working together to overcome Bokkun's pranks and they all learn a valuable lesson about friendship and sportsmanship.
One common theme could be the exploration of their different personalities. Bokkun might be a bit of a troublemaker while cream could be more gentle, and fanfictions could play with how they interact based on these traits. For example, Bokkun might get into a scrape and Cream has to bail him out, which deepens their bond. There could also be themes of mutual support and understanding as they face various challenges in the fictional world they inhabit.
I'm sorry, I don't have specific bokkun x cream fanfiction to recommend directly. You can try searching on some well - known fanfiction platforms like Archive of Our Own (AO3) or FanFiction.net. There might be a variety of stories created by fans there.
Eggman Nega could be a great main antagonist. He has the intelligence and the desire for power. He could find a way to open portals between the Sonic X and Sonic Boom universes to steal resources and technology from both. His plans would force Sonic X's Sonic and Sonic Boom's Sonic to team up against him. He could use his robotic creations from both universes, combining the advanced tech from Sonic X and the more rustic, yet effective, machines from Sonic Boom.
Dr. Eggman could be a great main antagonist. He could be using the chaos of war to further his own plans for world domination. He might be creating powerful war machines and using them to take over different regions, forcing Sonic and his friends to fight back to protect the peace.
A new character could be introduced as the main antagonist. For example, a being from another dimension who has been observing both Sonic's and Megaman's worlds. This being realizes that by combining the chaos energy from Sonic's world and the advanced robotics technology from Megaman's world, it can create a new, all - powerful empire. So it starts to manipulate events in both worlds to bring about this combination, while Sonic and Megaman have to stop it.
Dr. Eggman and Dr. Wily could team up. Dr. Eggman has his mechanical creations and knowledge of Sonic's world, while Dr. Wily is an expert in creating powerful robots in Mega Man's world. Together, they could be a formidable force against Sonic and Mega Man.
Well, obviously Dark Gaia itself could be the main antagonist. It has the power to cause chaos and destruction, and Sonic would have to stop it from wreaking havoc on the world.
Dr. Eggman would be a likely choice as he often causes trouble for Sonic. In the context of Secret Wars, he could have found a way to connect Sonic's world to other dimensions and start the wars to finally defeat Sonic once and for all. He might be using new and powerful machines he has created from the combined technology of different dimensions.
Dr. Eggman would be an obvious choice. Since Sonic is now in a more vulnerable human form, Eggman could see this as the perfect opportunity to finally defeat Sonic and take over the world. He might come up with new devious plans, like creating robots specifically designed to target a human Sonic.