Here is the FINAL part to the Loke x CelestialSpirit!Reader story. Enjoy!
Word count: 1580
'...' : thoughts
(Y/n)'s scar on her back healed nicely within several minutes. Loke had been worried the entire time the fight, despite the fact that the wound healed on its own. Now, only a faint, darkened area on the skin is left as a reminder of the horrible, tedious battle against the undead mages.
The battle had ended with a bang, literally. Natsu accidentally hit a barrel of oil that someone had placed beside an old cabin. His flaming ball of magic set off a chain reaction of explosions, leaving the land barren and nonexistent of any life. Team Natsu immediately cleared from the scene to avoid getting caught red-handed, seeking refuge in Lucy's apartment until the next day.
As always, none of the team members asked before barging into the blonde's living space. They got comfortable and gave themselves permission to raid the kitchen. Erza, with Gray's unwillingness to help, took the liberty of cooking a meal large enough to feed 10 men. Natsu, of course, dug in as soon as the dishes came in contact with the table's wooden surface. More than half of the meal became digested into the pink haired dragon slayer's stomach before any of the other members neared the table.
Angry and hungry, Gray started to maul the "hungry, idiotic lizard," as he was dubbed by the Ice Make mage, when Lucy screeched for him to stop. She pulled out a key and summoned (Y/n) the Tiger. Noticing the confused looks on her friends' faces, the blonde explained how (Y/n)'s a wonderful cook. With raised eyebrows the team watched with amazed expressions as the tiger spirit turned scraps of food into a meal fit for a king.
---
"Ahh," Gray sighs, happily patting his full stomach,"I've never eaten a cooked meal as great as (Y/n)'s. That was beyond delicious!" His once chiseled abdominal muscles are now disappearing behind an enlarged stomach full of food.
"(Y/n), when did you learn how to cook like that! The food was amazing," Erza compliments with a smile.
"Hehe... Loke and I enjoy indulging ourselves in human cuisines, so I went to a restaurant and asked for one of the chefs to teach me how to make delectable dishes like he does," the spirit replies with a flushed face. "I had to borrow a lot of Lucy's jewels to pay him, but it was worth it. As payment, I cook meals for her whenever she summons me in her home." Without another word, (Y/n) returns back to the celestial spirit world on her own, leaving Team Natsu to converse with one another.
"That's an awesome deal ya' got there, Luce," Natsu comments, a hint of jealousy and drowsiness laced in his voice.
"..."
"Lucy?"
"..."
"Lucy!"
"Huh!? What?!" Lucy screams, starting.
"I was talking to you, Lucy. What are you doing that's so interesting that you are ignoring us," the pink haired male inquires.
"(Y/n)'s key... It's all dirty," she mutters.
"Then wipe it off."
"That's just it! I can't remove the grime!" Lucy angrily mutters through gritted teeth, furiously scrubbing the Tiger's key with a damp cloth. "No matter how hard I try to clean it, nothing is coming off!"
"Let me see it," Erza calmly states. The scarlet haired mages takes the key from Lucy, examining it carefully. She runs an armored finger over the key's surface, a rough scratching noise confirming her suspicions. "It's rusting." The widening of Lucy's eyes surprises her friends, especially Erza.
"Ehhhhhh??!! Why is it rusting!? Gold cannot rust!" Exclaiming loudly with anger, Lucy stares at (Y/n)'s key in bewilderment. Like she had said, only the Tiger's key has begun to rust. None of the other keys that the blonde has gotten have a single speck of rust. Not even the gold ones.
"Maybe," Happy pipes up, suggesting a sudden epiphanic idea that came to him,"you should ask Loke or (Y/n) about it, Lucy. They would know something about it."
"No, I don't want them to worry more than they already are about things. (Y/n) just started a new life here. I don't want to disrupt that." Lucy explains, putting her foot down on the subject matter. "None of you are allowed to say anything!"
"'Kay."
"You got it, Lucy!"
"Whatever."
"Aye, sir!"
---
Over time, Lucy has introduced (Y/n) into more and more battles to fight alongside other celestial spirits. The Tiger spirit had a rocky start, but gradually adapted to her new life as a partner with Lucy, not a shield for Lucy to hide behind. Loke, along with the other spirits, pitched in to help (Y/n) as well.
Occasionally, (Y/n) got hurt. Whether it was a scrape, bruise, bone fracture, or laceration, there would be some form of injury that she would always bring back from the battle. Being the worrying boyfriend he is, Loke always scolds her afterwards. (Y/n) never takes the scolding to heart. She is well-aware of Loke's caring nature and experienced with the same treatment in their past life under Karen's abusive ownership.
Lucy, unfortunately, never noticed the small, progressive change occurring with (Y/n)'s key. With every injury inflicted upon the Tiger, her key deteriorates more. Unbeknownst to Lucy, the rest of Team Natsu, or any the celestial spirits, the rust wasn't just coating the surface of the key. Unlike normal rust, the fact that the key is made of gold isn't stopping the oxidation. Inside of the key, all the enchanted metal is being eaten away by the abnormal rust. From its outer appearance, the key just seems to be rusted, which is nothing close to its actual state.
The key's deteriorating state is analogous to (Y/n)'s well-being. After a long battle, the Tiger would find herself even more tired than after the previous battle. She just brushes it off, believing that she just needs to rest more, but the extra rest never helped. Eventually, (Y/n) began arriving to fights with bags and dark circles under her eyes, standing in a slouched position until needing to engage in battle.
Her condition worsened tenfold after two months went by. It has gotten to the point where Lucy refuses to summon (Y/n) into battles anymore. Once glimpse of her weathered down appearance makes the blonde mage's heart shatter, along with Loke's. The lion spirit tries to help his girlfriend, but there's only so much he can do for her. It's hard to help someone when a person doesn't know what is wrong.
---
On a beautiful day in the Fairy Tail guild hall, all of the guild members are conversing with each other while drinking and having a great time overall. Some of the members host friendly duels while others sit back and chat over various topics.
(Y/n) and Loke, as well as Lucy's other spirits, take part in the relaxing day at Fairy Tail. The couple sat themselves against an old oak tree and are currently cuddling. Loke's arms are wrapped around (Y/n)'s frail, weakened form. He stares and his lover while racking his brain for possible reasons to explain her deteriorating health. The assumption of her key rusting comes to mind, but Lucy never mentioned anything of the sort to him, so he casts the idea aside.
'There's no way that would happen... Though (Y/n) has been weakened due to Karen's maltreatment, she should have healed... Right?'
A sudden, shrill scream, along with (Y/n) going limp in his arms, alerts the lion spirit. As if to answer his question, Lucy runs over to Loke with an object wrapped in a cloth. She skids to a stop, but Loke doesn't see her panicked face. His attention is focused on his unresponsive girlfriend.
"Loke! (Y/n)'s key!! It turned black!!" Lucy cries out. She thrusts forward an open palm to display the blackened, unrecognizable key. Not a single inch of its surface shows its former golden shine.
"I-I... I didn't think this was happening," Loke murmurs. "Why didn't you tell me, Lucy? WHY?!" The lion spirit's voice raises in volume and anger. Words can't describe how he feels. His blood is boiling with rage at Lucy, but a small, rational part of him knows it isn't her fault.
"Y-You and (Y/n) were w-worried enough a-as it was," the blonde stutters with fear. "I-I kept quiet about it, think th-that it w-was nothing. Now, I c-can see that I was w-wrong. I'm s-sorry, L-Loke!"
"Sorry isn't going to help her! You're apology won't bring her back!!" Hot tears pour out of Loke's eyes, which he shut in anguish. All Lucy can do is hang her head in shame as Loke hugs (Y/n)'s body to his chest. "B-Be glad she'll be reborn e-eventually..."
"Reborn?"
"Y-Yeah... When something like this happens, which is very rare, a celestial spirit will be reborn a century later."
"Oh..."
Knowing that (Y/n) will be reborn let Lucy's heart rest a little easier, but she still feels guilty. Not telling Loke about the rusting was definitely the wrong thing to do.
'Well, in her new life in a century, maybe she and Loke will have a better life together. Maybe...'