"Past lives... an evil snake like man... ninjas... Luffy and the rest discover that in their past lives they were ninjas and they have some unfinished business that they need to perform." - Summary on FanFiction.Net
Souls Reborn is a Fan Fic by Emma Iveli. It is a Cross Over between Naruto and One Piece. The premise is that around ninety or so years ago, the Konoha 12, the Sand Siblings, and Kakashi were all killed by Orochimaru one by one during a Final Battle. However, afterwards, a woman appeared before Orochimaru and told him that due to his many injustices, the sixteen ninja he killed would be reincarnated, and one day unite together again to kill him once and for all. Then, she gave a scroll to the other two Sannin, which would make them immortal and young, so they may wait for the reincarnations and help them train for their final battle with Orochimaru.Now, the reincarnations have started to gather - and at their head is a certain crew.Last Update: 3/28/13.
Acceptable Breaks from Canon: For Naruto: Orochimaru killing the sixteen ninja and being the main villain in general, along with Kyuubi doing a Heel-Face Turn due to being stuck in limbo. This story was published long before the current events of the manga.
Adaptational Villainy: Orochimaru, in a sense. He was always a villain and a major threat, being the Big Bad for Part I of the manga, but him killing the sixteen ninjas is a little hard to imagine considering that in the current arc, he doesn't hold a candle to Tobi and Madara, or to Naruto who is probably the strongest ninja in the world after the two aforementioned. However, it's justified in that this Fan Fic was published in 2006, back when the Akatsuki was extremely mysterious, Naruto's true potential strength was unimaginable at the time, and he seemed to be the real Big Bad of the manga. If Emma had published this story anywhere between 2008 and now, Tobi and/or the Akatsuki probably would have been the main villain(s), having been a far more menacing threat and a much deeper impact on the overall plot of the series.
All Men Are Perverts: Jiraiya, Sanji, Wapol, Eyelashes, but the most surprising was Ginta, Gaara's reincarnation.
And Zoidberg: Kakashi was the only mentor/sensei to be killed out of the main cast of Naruto. Chopper is the only member of the crew that doesn't know any ninjutsu.
Arc Villain: As Crocodile is obviously far less of a threat than Orochimaru, and considering that only eleven of the sixteen ninjas have reunited as of the Alabasta Arc, this is his most likely designation.
Badass Crew: The crew is even more badass than the first time around, considering that they all now have access to jutsus and way more people.
Curb-Stomp Battle: Kuromarimo had a boxing match against Tsunade. You can guess what happened.
Mr. 3 vs Ace. Mr. 3 is so badly outclassed that he's deluded himself into thinking that he'll win and get a promotion.
Crocodile vs. Four-Tailed Luffy would have been this had Orochimaru not foreseen the possibility of it happening and gave Crocodile something that allowed him to actually harm Luffy when he's in that state.
Dark and Troubled Past: Sasuke's past has not exactly endeared Ace to his past life, and it's not hard to see why.
Dead Guy Junior: Ms. Goldenweek's real name is Temari, due to her father being from the Land of Wind. Her mother was named after Ino, because her grandfather, Sai, was in love with her until her death.
Did Not Think This Through: Crocodile did not heed the warnings of Ms. All-Sunday (who knew far more than he did about what kind of a man Orochimaru was) and accepted an alliance with Sound. The fact that he knew absolutely nothing about the Hidden Continent or Orochimaru is what made him into the Sannin's Unwitting Pawn.
Dirty Old Man: Jiraiya, of course. Due to his immortality, the Icha Icha series now spans over fifty books. And of course, being Kakashi's reincarnation, Sanji is a huge fan.
Elemental Powers: The joys of having both devil fruits and elemental ninjutsu in one fic.
Blow You Away: Luffy's been practicing with his wind chakra. And of course there's Tashigi, being Temari's reincarnation and all.
Enemy Mine: Tashigi is willing to cooperate with pirates considering the situation. However, it soon became clear that she may be joining the Straw Hats due to being declared a traitor and pirate by the marines. Then there's Zoro, who she has Belligerent Sexual Tension with.
Eviler than Thou: Crocodile doesn't hold a candle to Orochimaru and, unfortunately for him, he found out too late.
Flanderization: In-universely acknowledged and subsequently lampshaded. Despite being his reincarnation, Luffy is far more idiotic and annoying than Naruto ever was.
Hijacked by Ganon: Once Crocodile accepted an alliance with Orochimaru, there was no doubt who was truly in control.
Idiot Hero: Luffy, as Naruto's reincarnation. Was anyone really surprised?
Irony: The fact that the entire crew were all reincarnations is in itself irony.
Sasuke was a definitive prick, while Ace is arguably the nicest person of the main cast, Temari is graceful, while Tashigi is a klutz, Sanji can't get a girl to save his life while Kakashi was a total babe magnet...you get the idea.
Jerkass / Jerk with a Heart of Gold: Sasuke. Sure, he may have died trying to stop Orochimaru and was close to the other fifteen ninjas in life, but their current incarnations have no shame in admitting in that he was, well, a prick. Ironically, his current incarnation, Ace, is probably the nicest out of all the male incarnations. As for the current incarnations, the closest to this trope is Ginta.
Crocodile. When Vivi asks him about how all the suffering he made her country go through basically amounted to nothing and was now pointless due to the change of objectives by Orochimaru, all he does is laugh.
Loads and Loads of Characters: A given. The current main cast spans over thirteen main characters, and they've only reunited eleven of the sixteen reincarnated ninja. If you add the missing five plus the others who are obviously going to end up traveling with them, you have over twenty main characters. That's not counting all the supporting characters and villains that are likely to appear or already have, including the characters from Sound.
Locked Out of the Loop: Smoker doesn't know anything about the legend of the sixteen reincarnations, and Tashigi won't tell him (probably because he wouldn't believe her). As such, Tashigi has now been branded as a traitor and a pirate.
Chopper, seeing as he's the only member of the crew currently who has no knowledge of ninjutsu or ninja history.
The Lost Lenore: Ino was this to Sai. It took a while for him to get over her, as he married very late in life, and he even ended up naming his daughter after her.
The Man Behind the Man: Anyone who knew anything about Orochimaru knew the moment Crocodile accepted that alliance, Orochimaru had gained control of Baroque Works.
Odd One Out: Kakashi is the only sensei that was killed and reincarnated. Asuma was dead already, Kurenai was raising the kid she had with Asuma, and there has no mention of what happened to Gai.
Official Couple / Reincarnation Romance: Subverted in two cases. Emma Iveli ships both NaruHina and SasuSaku, so both couples occurred in their past lives. However, since Luffy is celibate, Kaya is in love with Usopp, Kiba's reincarnation, and both Nami and Ace clearly have no attraction to each other, the chances of either couple happening in this life are zilch.
The last two cases, ShikaTema and NejiTen, have tons of Ship Tease, which is unsurprising considering their reincarnations are Zoro and Tashigi and Kohza and Vivi.
Oh Crap: The general reaction of everyone when they realized that Crocodile pissed off Luffy, to the point that he went four-tails straight off the bat.
Original Character: Ginta, Gaara's reincarnation, who was created because Crocodile had already eaten the Suna Suna no Mi, and Emma didn't want him to be the reincarnation considering how much of a bastard he is.
Past Life Memories: Each of the reincarnations see theirs in dreams, and once they realize they aren't dreams, they become a lot more vivid and clear instead of disjointed.
Raised by Wolves: Ginta's parents were killed by a sandstorm, so he was pretty much this. He learned how to talk thanks to sailors down at the port (which is why he's such a potty mouth), and survived in the desert with his awesome sand powers.
Reasonable Authority Figure: Smoker. Once he gets a scope about the situation and realizes that Tashigi may have merit in joining with the Straw Hats, he immediately starts searching for more information, particularly where the legend of the sixteen reincarnated ninjas are concerned.
Reincarnation: Duh. Three guesses for who Luffy is, and the first two don't count.
The Reveal: Ms. Goldenweek, aka Temari, is the granddaughter of the "thirteenth" member of the Konoha 12, Sai the Artist, one of Naruto's best friends in life. The teachings of her grandfather and being the only one (asides from Ms. All-Sunday) who knew about Orochimaru's true nature and power is what lead to her pulling a Heel-Face Turn.
The Trickster: What Kyuubi ended up becoming. He once made Luffy do the Sexy no Jutsu on the promise of meat - though to be honest, it only worked because Luffy is an idiot.
True Companions: The bonds of those sixteen ninjas transcended lifetimes. It also extended to Sai, who was known as the "thirteenth" member of the Konoha 12, and who Naruto prevented from joining the battle that killed them. His last request to his granddaughter, Ms. Goldenweek, was that should she ever meet their reincarnations, she'd tell them about how he lived his life.
Unwitting Pawn: Crocodile, who, unlike Ms. All-Sunday, doesn't know a thing about Orochimaru or the Hidden Continent, which is why he made the mistake of making an alliance with Sound.
What Happened to the Mouse?: There has been no mention of the Akatsuki at all asides from allusions to Itachi. This was due to the Akatsuki being mysterious and rather unknown when the fic was published.
Kakashi was the only sensei to be killed alongside his students. While it's obvious Asuma was already dead and Kurenai is raising their kid, what happened to Gai?
Who Wants to Live Forever?: Orochimaru, of course, which is why Tsunade and Jiraiya burned the scroll with the jutsu that gave them immortality after using it.