There might be some extremely rare and niche fan - made stories with this idea, but it's not a common or well - known concept in the Mario fanfic community. Mario games usually portray Princess Peach as a damsel in distress who needs to be rescued from Bowser, not in such a complex and inappropriate - for - the - franchise relationship as the one described in this title. So, in short, it's not a mainstream fanfic topic.
If such a fanfic exists, one possible theme could be the shock and chaos it would cause in the Mushroom Kingdom. The Mario characters would have to deal with this unexpected and unthinkable situation. Another theme might be about identity, as Bowser Jr. is the son of Bowser and for Princess Peach to be in this situation would completely redefine her relationship with both Bowser and the kingdom.
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.
You can try fanfiction websites like Archive of Our Own or FanFiction.net. They have a wide variety of fan - created stories, including those about Bowser and Bowser Jr.
Some fanfictions might take a more comical turn. Picture Bowser and Bowser Jr trying to host a party in their castle but everything goes wrong. From the invitations getting lost to the food being ruined, it's a hilarious take on their characters.
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.
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.
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.
Growth and self - discovery are also common themes. He might start as a bit of a troublemaker but through his experiences in the fanfiction, he learns more about himself and grows as a character. Also, friendship can be a theme. He could make unexpected friends during his adventures, which helps him see things from different perspectives.