After reading a Nanatsu no Taizai Gaiden: Ban's Sidestory, I've been thinking of "What If Elaine were to drink the entire cup filled with waters of everlasting life and became immortal instead of Ban as he intends her to do to save her life during the fat clown-like Demon's attack on the Fairy King's Forest and after defeating the Demon, Elaine felt sad of Ban's death and turned herself in to the kingdom of Liones who accuses her for destroying her own country and taking the Fountain of Youth for herself and sentences her to death. Eventually she would become a member of the Seven Deadly Sins as the Fox's Sin of Greed instead of Ban?"

Might be a good AU story don'cha think? I hope so.

Disclaimer: I do not own Nanatsu no Taizai at all. The awesome manga belongs to Nakaba Suzuki.

Enjoy! ;-)

Chapter 1

Opening her eyes, a small young blond-haired girl with orange eyes clad in simple jail clothes awoke in her cell, heavily guarded by knights and soldiers of the kingdom with few items in her possession. As she helped herself up, the girl rubbed her temple after experiencing severe headaches to ease the pain.

"Oww my head really hurts" as she still rubbed her head "Never thought being an immortal can feel that headache. Ugh." the girl commented.

Then she noticed a tray of food and water being given to her daily by a routine shift on the floor and her stomach growled.

"I'm kinda feeling hungry anyway" as she picked up the tray and began to eat. While chewing and drinking, the girl began to recall everything what she knew within her mind: she is no ordinary girl or even a human at all, she is a fairy or to be exact an immortal fairy.

Her name is Elaine, the Guardian Saint of the Fountain of Youth and sister of the Fairy King Harlequin. Currently she is in prison for the crime of greed, accused of destroying her own country and taking the Fountain of Youth for herself by the kingdom of Liones who was in alliance with the fairy nation.

Having recalled who she was, Elaine also remembered that yesterday was her 33rd execution lately which involves being dismembered brutally but it failed to kill her once again like all other executions due to her immortality. Although her race, the fairies are immortal who can never age or feel sick but can be killed by physical means like murder, Elaine was a special case: she drank the waters of the Fountain of Youth, her country's national treasure and the source of life for the sustainability of the Fairy King's Forest and became truly immortal, never to die from murder or disease at all, the aging is another thing since she already lived 700 years before drinking the cup.

"Those humans didn't get, how they call it, the memo that I can't be killed by any means of execution and yet they still continue to do so 33 times lately!" as Elaine sighed of the human stubbornness.

But it wasn't her entire fault to drink the whole cup. Elaine did this because a man who was famously known for his constant thievery in Britannia told her to in order to save her life during a Demon's attack. That man's name is Ban, the one who destroyed her depression for 700 years in just seven days of interacting with each other.

Looking out in a small window of her cell, Elaine began to recall that moment like if it was yesterday...

"Oh Ban why did you leave me alone in this world?" she said as tears in her eyes began to flow.

700 Years ago

In the Fairy King's Forest, Elaine watched with tears in her eyes as her brother Harlequin about to leave when she and her fellow fairies watch as their Fairy King leave.

"Big brother, please don't leave me! Don't leave alone to guard the Fountain without you!" as she tried to plead Harlequin not to go.

"But I can't! Helbram and the others are in danger. I can't leave them like this!", Harlequin justified his reason to leave as he flew in full speed to rescue his best friend Helbram.

"Brotheeerr!" Elaine cried in grief.

As a result, Elaine had guarded the Fountain of Youth for 700 years in solitude, having thwarted all attempts mostly by humans: a aging king desiring immortality sent an army to invade her home, a merchant who dreamt of endless riches and attempted to steal the Fountain of Youth from her; and finally a savage tribe attempted to burn the Fairy King's Forest down with her to take the national treasure for themselves.

All that changed when she met Bandit Ban...

20 Years ago

At the Sacred Tree, a young man climbed up the tree of humongous size by hopping from branch to branch with a merry look on his face and a sing-song tune in his voice.

"A lick will add ten years to your life. A swallow will add a hundred years to your life. Drink it all and you'll live foreveeer!"

Finally reaching the tree, the young man set his bag on top of the tree and was about to help himself up.

"There! According to Zhivago's info, on top of this tree, is where 'the treasure protected by a saint' should beeee!"

On the other hand, Elaine noticed his presence and stared at him innocently. The man stood up and stared at her for a few minutes before laying his eyes on the Fountain of Youth.

"Oohh! There's the treasure, 'the Fountain of Youth! If you drink the water flowing from the cup, you'll be granted eternal life...huuh? Although the story seemed exaggerated, there's no saint protecting the treasure" the young man looks him awe at his prize. Hearing this, Elaine began to make her move as the bandit looked at her and asked "Are you lost little girl?"

"I'm protecting the Fountain...", Elaine spoke innocently as she levitated much to human's astonishment. "From bandits like you" as she raised her hand that summoned hard winds to blow the man away.

"Wha- wa..wait!" the human bandit tried to resist the force of the wind conjured by Elaine and flew right off the Sacred Tree. "Whoaaaa! I'm gonna diiiiiieeee! the man cried frantically as he fell.

"Don't worry. Even if you die, you'll continue to live on as part of this forest" Elaine said after easily blowing off the bandit. Noticing a change in the clouds. "Those clouds looks ominous though..is it a sign" as she wonders but loses her though when she saw the bandit climbing back up again repeating the same words again just like the last time before sending him flying away again. The human persistently climbed back again and again and again as Elaine repeatedly blew him off until they're both annoyed.

"Knock it off already!" the human bandit exclaimed. "That's my line!", Elaine retorted. Both silently called each other 'so annoying'

"And how are you still alive? No human should be able to survive after falling from this height!" Elaine demanded an explanation from the human.

Weeeeeel...I'd get caught in a branch, or get cushioned by a cluster of trees or get lucky and fall on top of a Giant King Trumpet Mushroom.

"...No way...why would this forest protect a human...?" Elaine looked in disbelief of what the human just said.

"Kah Kah! How should I know?" the bandit couldn't know the answer but readies his three-section staff continuing "...But it's surprising that you, little miss, would be the guardian of the treeeasure. Now matter how you look at it, you're more a little girl than a saint, but...I won't hold back against youu!"

"A weapon imbued with power.. Kill and steal...All humans think are", Elaine thought in her mind. Then the bandit swings his weapon in a kung fu-fashion, Elaine raised her hand to attack. But instead of attacking Elaine, the human used the three-section staff to swiftly take the cup as fast as lightning and sniffed at it "It's..not alcoholic. Too baad"

Elaine saw this and realized that the bandit took the cup without noticing as she turned around to see where the Fountain was placed upon was missing.

"N...No!" she cried in panic. "Cheers to my long and prosperous li-" the young man said cheerfully as he was about to drink the cup but was cut off when Elaine immobilized him by summoning the tree's branches on him. "-fe?" his sentence was finished.

Elaine sighed in relief as the bandit tried desperately to break free "THE HELL IS THIIIIS!? HEY! LET ME GO!"

"I don't expect you humans to understand...but without this Fountain of Youth, the forest will die!" Elaine explaining to the struggling man.

"Oh, I got it!" the man exclaimed just after a few seconds much to Elaine's surprise and disbelief.

"I...I got it? That's such an obvious lie!" Elaine believed that the bandit is lying.

"Noooo, I'm serious!" the person said defending himself.

"What a foolish human..He doesn't even know that we fairies can read the hearts of humans.." Elaine thought as she is confident that the man is clearly lying of his words, reading his heart.

But instead of lies, Elaine heard truthful words in the man's heart. Oh well, I guess I have to give up..

"Huh?" Elaine mentally thought in surprise. "The ale made from the forest's wild-berries is reeeeally goooood.." as he commented but deep in his heart Maaan, what a wasted trip. He continued to comment in his current situation. It'd be a shame if I couldn't drink it anymore...

And there's something bottomless that spreads in this man's heart she mentally said before releasing the human off the branches he was trapped in much to his surprise.

"Who...are you?" Elaine asked. "Can't you tell by looking? I'm a bandit! Bandiit!" the human retorted at such a dumb question.

"That's not what I meant. What's.." she said trying to ask his name again before he finally answered.

"I go by Bandit Ban. You little girl" Ban said as he relax his shoulders from the stiffness he'd endure by Elaine's branches.

"I'm not a kid..and it's Elaine" she gave her name to Ban. What a weird human she thought.

As the two settled down and talked with Ban hanging from the branch and herself floating in the air as Elaine wonders aloud. "I wonder what happened..How was a human let through? Until now, the Forest has never let a single person with malice in...an aging king dreamt of ruling forever and sent an army to invade... a merchant dreamt of obtaining endless riches and attempted to steal the fountain of youth... a savage tribe attempting to burn down the whole forest with me"

Turning to Ban, she asked. "What's your reason...for wanting the Fountain of Youth?"

"Hm, well...even though my life hasn't been all that great, if I live long enough..something good might happen...something like that. That's about it" Ban replied to her question. Elaine saw the truth of his words in his heart as she saw Ban living a life of poverty, forcing him to resort to steal from people to survive, some of them left him beaten up.

"But what if you obtain immortality...and even then nothing good happens to you?" Elaine asked another question. "Ahn?" Ban responded.

"I've been protecting this forest and the cup in place of my brother, the Fairy King of this forest...for several hundred years, nothing good has ever happened to me at that time." Elaine told Ban of her status as a Guardian Saint.

"Wha...seven hundred years?" Ban said as he looked in surprise. "...Are you shocked? Even though I looked like this, I've lived a life ten times longer than you have" Elaine said as she hung her head down.

"That must be boring as hell!" the bandit exclaimed of her solitude life which caused Elaine to tilt over her floating position and being irked by his words.

"Tha...that's what you had to say...? It's the first time anyone's said that to.." the Guardian Saint trying to control her temper but sadly it failed. "OF COURSE IT'S BORING! BORING BORING BORING! I HAVE NO IDEA WHAT'S BEEN HAPPENING OUTSIDE THIS FOREST FOR THE PAST SEVEN HUNDRED YEARS!" Elaine yelled at Ban in an outburst before panting in tiredness of her release of hot air.

Ban on the other hand, nearly fell off his sitting spot when his ears got caught in Elaine's sudden outburst had not for his reflexes. "...She's too much for me..." the young man said out loud before hopping down from the Sacred Tree. "Hey!" Elaine tried to get Ban back but assumed that he won't be coming back.

Elaine could only watch and sulk in sadness. "I wish...he had stayed and talked a little longer..." she thought out loud.

Sitting alone near the Fountain of Youth, Elaine was greeted by book shown by Ban in her face. "Tadaaaaa! This is the label of the Aberdeen ale that I was talking about earlier. The bittersweet fragrance of the wild-berry is amazing! No matter how much you drink, you'll never get wasted. I got some from a long time ago from Zhivago, a guy I met in a prison in Aberdeen. If I have never gotten to try it, my whole life would have been a waste!" the young bandit explained the contents from the book he had showed to Elaine.

"And the next page is.." Ban continued before being interrupted.

"...Ban!" Elaine exclaimed in shock "Wh- why?" she asked.

"This is my secret treasure that I dropped before you blew me off...my Ale Label Collectiooooon!" Ban explained his reasons.

"That's not what I meant...why did you come back?" Elaine asked one more time after receiving a different answer. "I wanted to show this you people of the Boredom Clan." Ban quickly gave his answer. Looking at his ale collection, Ban frowned, "But no one understands how amazing this thing is..." Elaine slightly chuckled. "...Hey can you show me some more" she asked.

"Alright! That's what I'm talking abouuuut!", Ban exclaimed with excitement. He's a really weird human, Elaine thought.

In seven days, Elaine and Ban interacted with each other; telling about her brother to Ban, being quite embarrassed to see the man in his birthday suit when Ban asked her to go for a swim together, talking about the Goblin a dark ale being the most famous one and its bitter taste of the roasted wheat is the ale's selling point, explaining to Ban about the almoca leaf and even about the concept of human greed. At that time, Elaine started to develop feelings for Ban, one of those moments she was both embarrassed and upset that Ban can't even tell how she felt resulting to weakly pummel him to no effect.

After seven days, Elaine sighed which Ban doesn't seem to take it lightly. "Hey, heeey, are you getting bored only after seven daaays? We're only halfway though the book!" playfully berated her.

"Tha...that's not it! It's just...you see, I don't even drink, so I feel like I'm becoming an expert in something useless for me..." Elaine quickly defended her reason to sigh.

Ban appeared to buy that and Elaine tells him that she enjoyed his stories and felt like she was on a journey with him. When Ban get up to find food, Elaine showed a glad look on her face but didn't notice a dark presence coming to the forest as she was reading half of the book left.

Elaine spoke out loud that she wished Ban came to steal her instead of the Fountain of Youth, which Ban, having found some cowberries quite fast, overheard and asked her if she wanna make that happen much to her embarrassment. When Ban decides to make it happen, Elaine tells him not to make fun of her. But Ban states that he's serious and called Elaine the first person to really listen to what he has to say since he doesn't get along particularly well with other people.

With a huge blush on her face, Elaine was excited but tells Ban that she can't leave the Forest due to her duties as the Guardian Saint of the Fountain but Ban quickly makes a proposal that he'll find her brother and bring him back that will relieve her of her duties. Hearing his words, Elaine quickly hugged him as her way of thank you.

Then suddenly, a large fat demon that looks like clown suddenly appeared, destroying the top of the Sacred Tree it landed and roared loudly before unleashing a demonic fire that caused tremendous damage to the forest and killed everything in its range of fire.

Elaine and Ban slightly manage to evade the Demon's descent as they try to help each other up.

"*cough* What..*cough* What is that monster?!" Ban frantically asked, having suffered from the fall earlier. "Ban! Pull yourself together!" Elaine said showing concern of his safety.

Answering to Ban's question previously, "The Forest of the Fairy King can't be burnt by natural fire...If it's being burnt..then it's "Purgatory Fire"! This unnatural power...there's no doubt about it" Elaine explained with fear of terror. "It's from the Demon Clan! They should have been sealed away after losing to the Goddess Clan in an ancient war...how is this possible?!" The Demon then took a look around with malevolent malice as if searching for something after gazing at its destructive power on the forest.

"Elaine! Where's the fountain?" Ban asked after listening to the fairy's explanation.

"Don't worry I got it!" Elaine replied, having already the cup in her hands or more precisely a branch she summoned to lift it from its place.

"That monster might be after it! Take the cup with you and run!" the man said as he brandished his three-section staff to battle the Demon.

"You too! The Demon hasn't noticed us yet!" the fairy tried to plead Ban not to risk their presence known to the Demon's view.

"Shhh! Thaaat's why we have to take it down in one hit!" Ban sing-song said as he swing around his three-section staff and made a war cry. He then ripped the heart of the Demon from behind and proudly displayed his supposed-victory. "See? One hit."

The Demon looked back to see its attacker right as Elaine was about to warn Ban "No, Ban! The Demon has more than one hea-" before the large monster fired a beam from its eye that sliced through Ban's arm and pierced Elaine's stomach without its victims' even realizing it.

"Ba..." Elaine trying to call out his name before collapsing.

"Ela..." Ban tried to call hers too before suffering massive blood loss.

As they lay severely wounded, Elaine tried to call out Ban and weakly handed over the cup. "Ban...Ba..n! Ta...Take the water..Please..drink" The fairy lost control of the branch carrying the cup before Ban managed to grab it.

Ela...ine, a wounded Ban said in his heart as Elaine can read what he says in his heart. Drink all...of the water...in.. the cup. You...need to live!

Elaine shook her head in disapproval but Ban insisted. I'm..no good. I don't..even have the strength..to drink it. ..That's why..you should.. The fairy reluctantly lifted the cup and began to drink all its contents till the very last drop. There...you go, Ban mentally thanked her for listening to him in his last moments before death.

But Elaine had other plans: she intends to transfer the Fountain's everlasting waters into Ban to become immortal instead of her..but before she can do that, the Demon made a huge stomp on the ground, sending the fairy flying. And when she crashed, Elaine realized her mistake: she gulped down the Fountain's waters intended for Ban right into her throat and her wounds healed right away, fully becoming an immortal! The Demon unintentionally fulfilled Ban's wish for Elaine to drink the entire cup to save her life.

N-no! No! No! No! This can't be! This can't be happening! I'm supposed to give Ban the cup's waters not me! Why?! Elaine was shocked and panicked that her plan to save Ban backfired and became immortal herself. Before she can panic further, Elaine saw the Demon about to pounce on Ban's body and horribly tear him to pieces and swiftly reacted to get Ban to safety. This puzzles the Demon of its missing prey for a while.

Good girl Elaine. Now get out of here while you still can! as the human bandit tells Elaine to escape but the fairy felt rage within her towards the Demon, turning to Ban and said, "Ban, hold on a little longer, it'll take a while" The Demon wasted no time as it lunged its deadly claws on the fairy only to be countered by a large tree branch resulting one of its fingers broken but its brute force managed to break through the tree barrier and gravely wound Elaine but it quickly healed thanks to her newly-acquired immortality.

Telekinetically lifting Ban's three-section staff with a lift of her finger, Elaine angrily yelled with her tears flowing at the demonic being. "You..you killed Ban and now I'M GONNA KILL YOU MONSTER!" Then the brutal battle between the fairy and the Demon exploded as both combatants fought with everything they got and no holding back of their immense powers both suffering heavy fatal injuries during the entire battle, causing resulting colossal damage in the Forest of the Fairy King.

In the aftermath of the battle, Elaine successfully killed the Demon, leaving its grotesquely-dismembered corpse behind while her seriously grave wounds healed quickly as if nothing happened to her with few remaining pieces of her dress remaining. Returning to Ban, Elaine tried to tend to his wounds but the man spoke to her in his heart. Hey, Elaine. You're an idiot. I told you to escape but you had to stay and fight that monster. Look at you you almost look like Swiss cheeese!

"I'm sorry Ban. But if I left you, that monster would have make you its human sandwich by now!", Elaine retorted of his berating. An immobile but still barely alive Ban smiled and later coughed in blood, alarming Elaine.

"Ban, stay with me!" the fairy visibly panicked of her human friend's serious condition. It's okay Elaine. At least that you lived. And..now that I know you're alive, I caaan goo and rest in peace Ban mentally told her in his heart, but Elaine started to cry. "Please Ban don't die on me! I've always wanted to be with you. I don't want to be alone again..Please..don't leave me alone, Ban. I beg of you" as she pleaded Ban not to die.

I was happy Elaine for being the first person to accept me who I am..Go to the world I told you about in my stories and see it for yourself, got it?... Ban happily said to Elaine in his heart during the last moments of life. Hey..Elaine..can you do that for me..

"Yes..Ban! I will! I lo.." Elaine complied to Ban's last wish but was cut off by his death. Elaine is now alone again in the world as the man whom she grown to have feelings for is now gone from this world as she shed her tears of grief and sadness. She later used her magic to preserve Ban's deceased body then placed it somewhere no one can find and desecrate his tomb with the name placed on it: "Ban". She also kept the almoca seed with her to plant it later when she felt like it.

Some time later after that.

"Criminal, name Elaine!", a voice yelled. That voice soon revealed to be the judge of the human kingdom. Elaine was under the custody of the kingdom of Liones carefully guarded by surrounding Holy Knights with chains in place of her hands after she willingly surrendered to a group of partolling Holy Knights sent to investigate the large black clouds of smoke over the fairy nation despite the treaty between two races to not cross each other's borders back at the ruins of the Fairy King's Forest.

"To satisfy your own greed, you destroyed the Forest of the Fairy King who had an alliance with us, and took the Fountain of Youth for yourself. In addition you betrayed your own country and your duty as the Guardian Saint! For your sins, you shall be sentenced to death!", the judge made his verdict of Elaine's sins.

The captain of the executioner Holy Knights approached Elaine and asked, "Any last words?"

"Last words eh? Well then, do you have ale? I would like to try it myself" Elaine playfully replied much to the Holy Knights' deadpanned of the fairy's last words.

And this is what happened to Elaine.

Present Day

Returning from reality, Elaine sat back on the wall and wiped away some few tears in her eyes. She brushed off the dust from the book revealed to be Ban's old ale label collection, her only memory of the good 7 seven days together with the man who changed her life. She began to read the halfway of the book she hadn't finished yet 20 years ago with the light provided by the cell's small window.

Elaine continued reading the pages of the book until the cell's doors opened.

Realizing this, she groaned of the same old routine performed again and said "Another execution again? You humans are certainly stubborn and foolish after all. Huh?" Elaine expecting the knights preparing another means of execution only see a short scruffy-haired blond boy with simple regal knight clothes, carrying a dragon-shaped sword on his back.

"A kid?" Elaine said in confusion.

"Elaine the Undead Fairy, you're coming with me." the blond boy demanded.

"What?!" Elaine exclaimed.

A young man demanding the immortal fairy to come with him! What does this mean? What is his motive? Find out in the next chapter! :)

Author's Note: All done, oh well in this AU story it's a What If story.

* Elaine accidentally drank the contents of the Fountain's waters intended for Ban when the Demon stomped its foot pushing her back and gulped it when she crashed.

* After gaining immortality, Elaine fights and kills the Demon in a bloody battle.

* Elaine is imprisoned for her sin of greed by the kingdom of Liones in behalf of the fairy nation who believed her to be responsible for the forest's destruction since she was the only survivor left in the scene of the crime.

* I might add the possibility of Elaine make her first try of ale just to sate her curiosity of it and ended up being drunk in her first drink. LOL.

* I based it off from Nanatsu no Taizai Side Story: Bandit Ban, so disclaimers it belongs to Nakaba Suzuki

* In the next chapter, Elaine joins the Seven Deadly Sins as the Fox's Sin of Greed, turns to human form for the first time based from a female Holy Knight who died in an ambush or battle for a long period of time like King and Helbram for example, wears her full body armor with unique helm in human form, and has a Sacred Treasure of her own (I might think of a name lately probably base it off from the Arthurian weapons)

Enjoy the story! ;-)