Well, it could be about Bowser Jr. losing a very important battle. Maybe he was trying to prove himself to his father, Bowser, but failed miserably. This failure made him feel so disappointed in himself that he couldn't hold back his tears. He might be crying alone in a corner of his lair, feeling like he let everyone down.
Perhaps in the fanfic, Bowser Jr. has his favorite toy or possession taken away from him. It could be a special item that gives him confidence or makes him feel powerful. Without it, he feels vulnerable and starts crying. For example, if it was a magical trinket that his father gave him and now it's lost, he'd be really upset.
Another possibility is that Bowser Jr. has a friend, a little minion maybe, who gets hurt. He really cares about this friend and seeing the friend in pain makes him break down and cry. He might try to be strong at first but then his emotions get the better of him as he realizes he might lose his friend.
One could be his father, Bowser. Bowser might be a main character as he could either be the cause of Bowser Jr.'s crying, like if he scolded him too harshly. Or he could be the one to comfort his son. Another character could be Luigi. Imagine Luigi somehow stumbles upon Bowser Jr. crying and has to decide whether to take advantage of the situation or be kind.
In this fanfic, Bowser Jr. might run away because he's curious about the outside world. He has always been in the shadow of his father and the Koopa Kingdom. So, he takes off to explore different lands, face new challenges, and in the process, he could grow as a character. He might even make some unexpected allies or enemies along the way.
His father Bowser could be a major character too. He might be searching for his son throughout the fanfic. There could also be other Koopa characters like the Koopalings. They could be on a mission to bring Bowser Jr. back or they might be secretly supporting his decision to run away.
In some fanfics, there might be a plot where Bowser Jr. tries to prove himself to Bowser. He might take on a difficult task on his own, like stealing a precious jewel from a well - guarded castle. This shows his growth and determination to be a worthy heir to Bowser. And it also adds a touch of family - like relationship exploration between them.
One possible theme could be family. As Bowser and Bowser Jr. are father - son, the fanfic could explore the dynamics of their family relationship. It could show how they support each other, or how Bowser is trying to raise Bowser Jr. to be a worthy heir.
One interesting fanfic could be about Bowser Jr. going on a solo adventure to prove himself to Bowser. He might encounter some of Mario's friends and have to use his wits to get out of tricky situations.
Sometimes, there could be original characters created by the fanfic writer. These could be other magical creatures or even some sort of mentor figure for Bowser Jr. who helps him develop his skills and understanding of the world around him, adding a new dimension to the relationship between Bowser and Bowser Jr. in the story.
Well, a 'bowser x bowser jr fanfic' could be about their relationship in an interesting way. It might explore how Bowser Jr. looks up to Bowser as a father figure. Maybe it shows them on an adventure together, facing challenges in the Mushroom Kingdom. For example, they could be trying to take over a new area and Bowser is teaching Bowser Jr. the tricks of the trade.
Some gaming forums also have sections dedicated to fanfiction. For example, Nintendo - related forums might have threads where fans share their Bowser Jr. and Bowser fanfics. You can interact with other fans there, too, and maybe even get some recommendations based on what others have liked.
There could also be fanfics that place Bowser Jr. in different universes or crossovers. Imagine Bowser Jr. meeting characters from other video games or even different kinds of fantasy worlds, and how he'd react to these new and strange environments.