Naruto is mind-blowingly complex. The franchise is comprised of two anime, a spin-off, a sequel, countless movies, and the original manga, so there's a lot to take in.
Even though one could watch Naruto for hundreds of hours, some fans of the ridiculously popular anime series series aren't satisfied with the official content. These devotees have crafted a whole world of creative Naruto fan theories to help flesh out some of the franchise's finer details.
Perhaps due to the anime's sprawling scale, there are tons of plot holes to fill, and plenty of characters who viewers don't know enough about. Naruto and Naruto Shippuden fan theories range from relatively tame ideas – like the identity of Metal Lee's mom – to the totally shocking assertion that the Infinite Tsukuyomi, a powerful instrument of mass hypnosis, never deactivated.
Redditor /u/awesomehuder offered up a fan theory that's worthy of a college literature class. Every member of the Akatsuki, a group of renegade ninja who harbor wildly different goals and motivations, represents a reason for people to wage war. The user breaks it down:
Pain & Konan — Peace.
Hidan — Religion.
Kakuzu — Money.
Kisame — Expose lies and hypocritical countries/nations.
Itachi — To protect your country/nation.
Sasori and Deidara — To be known in the world for creating diplomatic changes that last a long time (represented as bombs/terrorist attacks in countries and civil workers, politicians and soldiers being puppets of the government.)
Zetsu — Protect land and nature/territory.
Obito/Madara — Force their idealistic world traits onto other nations, to create an eventual and unified co-existence.
While Kakashi's father Sakumo played a major role in the shinobi's early childhood, viewers never find out who his mother is. There are two major theories about the non-Hatake half of Kakashi's lineage.
One theory from Redditor /u/ZacUAX suggests Kakashi's mother was a member of the Inuzuka clan. Kakashi regularly uses several canine-based techniques, like Lightning Release: Lightning Beast Tracking Fang, and also summons dogs to help him fight. Additionally, he has a powerful sense of smell that's comparable to Kiba Inuzuka's abilities.
If his mother wasn't a member of this beastly clan, she could be from Kirigakure. Kakashi constantly hides his face, which Redditor /u/Ruudkin theorizes might be because he has razor sharp teeth, just like the people from that country. While this theory is definitely a little out there, it's fun to think about, and is supported by Kakashi's proficiency with Zabuza's sword.
While most of the kids from Boruto have two identifiable parents, this is not the case for Rock Lee's son, Metal. In response to the ambiguity, some fans have theorized Metal's mother is Tenten, another member of Lee's first ninja team.
Of all the women in Lee's life, he's definitely closest to Tenten. The two have been on plenty of overnight missions together, so they had ample opportunities to be intimate. The theory is further supported by Metal's appearance — his eye shape doesn't come from his dad, but those eyes look remarkably similar to Tenten's.
On top of all this, metal is a key part of Tenten's fighting style, so perhaps Metal's unusual name was inspired by his mother's affinity for the material.
The Mangekyō Sharingan is an advanced version of the Sharingan that activates when a Sharingan user witnesses the death of a loved one. While it's assumed the dōjutsu is exclusive to the Uchiha family, this might not actually be the case.
After Obito Uchiha is crushed by a cascade of rocks, he asks his teammate Rin to remove his eye and give it to his friend Kakashi Hatake, as he hopes to pass the power of his Sharingan to Kakashi before he dies. Obito survives the incident, and his remaining Sharingan evolves into a Mangekyō when he witnesses Kakashi kill Rin.
Kakashi also cares deeply for Rin, and was forced to kill her against his will, so the event could have possibly caused his Sharingan to transform as well.
However, Kakashi doesn't activate his Mangekyō until he's in his late 20s. This could be because his lack of Uchiha blood means using the Mangekyō takes a heavier toll on his body, so he needed to advance his skills before he could wield the power.