Yes, there might be. The Naruto and Blue Exorcist fandoms are both quite large, and it's not uncommon for fans to create crossover fanfictions. You can try searching on popular fanfiction websites like Fanfiction.net or Archive of Our Own.
There could be. Since Naruto and Blue Exorcist have their own unique worlds and characters, some creative fans might be inspired to write a fanfic where Naruto has some connection to Rin from Blue Exorcist. However, it may take some effort to find it among the vast amount of fanfiction out there. You could start by using specific search terms on fanfic platforms.
I'm not entirely sure if there is a specific 'Naruto is Rin Blue Exorcist' fanfiction. But considering the popularity of crossovers in the fanfiction community, it's very likely. Many fans enjoy combining different fictional universes to create new and interesting stories. Check different fanfiction repositories and use relevant tags to narrow down your search.
Chapter 186, "The Goddess Who Can't Stand the Smell of Pig Manure", is the clearest early answer because it turns Smell's situation into a concrete plot event. The chapter gives readers a real answer by opening on Seeing Wen Jiaojiao bravely entering the pigsty, Jiang Yan couldn't...
Chapter 443, "Did Jiang Li Steal Team F's Home?", is the clearest early answer because it turns Team's situation into a concrete plot event. A useful checkpoint is the way the scene starts with Team D's captain, curious, turned around and was surprised to find...
Chapter 553, "His Love Runs Deep", is the clearest early answer because it turns Luo Xuan's situation into a concrete plot event. A useful checkpoint is the way the scene starts with His gaze shifted to Luo Xuan's empty hands, and Ai Xiaochun's...
Chapter 359, "You Know Who I Am and You Dare Speak to Me Like This?!", is the clearest early answer because it turns Is Sister Li's situation into a concrete plot event. A useful checkpoint is the way the scene starts with Why do I hear a scream?" "This is...
Chapter 593, "Don't Look, It's a Bad Review!", is the clearest early answer because it turns Don's situation into a concrete plot event. The chapter turns that into something concrete by moving from The night was cool, and the two had just emerged from the chilly...
Chapter 616, "I'm Going to Save Sister Xiao Wan!", is the clearest early answer because it turns Jiang Yan's situation into a concrete plot event.
Chapter 631, "It's Him Who Got Hurt, Then It's Fine", is the clearest early answer because it turns Hurt's situation into a concrete plot event. Early on, To avoid making a disturbance, the next second, Zhao Lang directly....
Chapter 558, "The Love-Struck, Flirty Wife Appears", is the clearest early answer because it turns Xiao Chun's situation into a concrete plot event. Early on, These people's comments are just too unpleasant; where does the fish....
Chapter 234, "Chasing Wind Youth", is the clearest early answer because it turns Chasing Wind Youth's situation into a concrete plot event. The chapter gives readers a real answer by opening on Given the vast mystical powers Jiang Li had displayed before, he was...
Chapter 173, "Su Yinwan, You Did It on Purpose, Right?", is the clearest early answer because it turns President Shang's situation into a concrete plot event. The chapter gives readers a real answer by opening on Jiang Li finally rose from her seat.