This is going to be something unlike anything I have ever written before. I don't really consider this an 'open', or polyamorous or whatever else people might call it, relationship, but I think it's more of a 'freebie'. It'll make sense, but please believe me when I say that this is the first time I've written like this, so please spare me some hate if it isn't done perfectly.
Without further ado, enjoy.
Expeditions are brutal trials, that leave everyone affected. The simple act of survival is enough to permanently damage a psyche. For that reason, simply making it back to the walls is reason enough for celebration.
Respectful and modest celebration, of course. There are still piles of dead to bury.
The newest scouts are hit the hardest. Their naivety and experience often renders the once hopeful troops hardened. The higher ups are nothing but lenient on them, and let them take as much time as they need to recover from these trips.
The superiors, however, find that while the expeditions never get easier, the coping mechanisms improve. Anything and everything is fair game once the horses ride on home. The most popular options are of course drinking and sleeping around, though other squad leaders find peace in documenting their journey, or even just using what little gas remains in their 3DMG to fling aimlessly through the trees.
Anything to clear the mind, but whether the mind is full of hate, sadness, or anger, or anything else, is up to the soldier. Erwin can relate. Once all duties are taken care of, the healing begins until the preparations for the next mission are announced.
This last mission was brutal, but paid off immensely. Hanji succeeded in capturing yet another live titan, and a supply route has begun to form. This was not without risks. Too many soldiers did lose their lives, but it was not in vain. The time to recover is now, and that's just what the Survey Corps. needs to do.
Hanji is more than happy to dive right into her research. Keeping her mind active with something productive is the best thing she can do. Her squad was able to stay alive, so her ability to focus is the least she can offer to her comrades.
Though for Levi, her studies are not enough to make his post-excursion worthwhile. What is a brief jaunt outside the walls to Humanity's Strongest?
All this pent up energy should be put to good use. For a while, he had spent it on her, but while Levi would prefer to exercise his body, Hanji would rather exercise her mind. Their opinions on what counted as being 'productive' varies greatly.
Levi isn't upset in the least that Hanji doesn't find his quick and forceful sessions productive. He wishes she did, but he can't make her.
Except for that one time he pulled rank and she lov- No. Not now. No point getting hot and bothered if nothing will come of it.
While Levi truly loves Hanji, it's hard for his eyes not to wander during times like this. Hanji finds it endearing, honestly. The fact that she knows by withholding from him makes him feel so deprived that he would go anywhere else makes her smile with sick power. She knows no one would take him forever with all those quirks.
She kisses him hard once they dismount the horses. He tries to prolong and deepen the kiss, but Hanji smiles as she breaks away and runs into the courtyard.
Frustrated as ever, Levi heads off to find something to do. It doesn't take him long. On the other side of the stables, Mikasa and Jean's squads are grooming the horses and there is a large pile of supplies to put away. Levi would be more than happy to help, but his mind has become stuck on the lithe woman in front off him.
Mikasa went from loathing Levi, to gladly working under the captain. Their fighting styles synced faster than either of them would believe. Once she understood that Levi had beat Eren for his own good, they have formed a respectful, and even amicable relationship.
Five years later, at twenty, Mikasa has honed her skills to become one of the youngest squad leaders in history, and for good reason. Once a ticking time bomb, Mikasa has now become nothing short of a lethal Jack of all trades.
Levi smiles from across the stable. She never sees it. She disappears out the door and off to do some other chore. Regardless, he helps Jean finish polishing the saddles. Once finished, Levi dips indoors to see what else can be done.
Wandering through the halls, his mind drifts back to Mikasa. As the stress of the mission began to mount, his attention to her physique began to grow. Not that he never noticed her strength, but now it is something to be admired. This physique of a soldier is hard to find, and once it is found, it never lasts. Mikasa is different. Levi knows it will take a lot to kill her, and he loves it. He needs a piece of her. He can't help it. He needs to show her he has nothing but the highest respect for her.
He doesn't want to love her, he wants to honor her.
This idea of honor and respect Levi has towards not only Mikasa, but to Hanji is something Hanji absolutely loves about him. Hanji knows he has thought this way for a while. She can read him like a book. Hanji could never feel threatened by someone fifteen years her junior, who has no real chance, nor desire to be with someone as Levi. True, they are a talented duo, but so is Hanji, and Levi knows this.
'Knowing' has just become part of their relationship. Levi knows how skilled Hanji is, and Hanji knows how truly loyal Levi is, so the day she knew Levi was casting his glance, she wanted him to know it was alright.
During an advanced training of new 3DMG features Levi was conducting, Hanji was on hand to treat any injuries should the need arise. She was pacing around like a stalking predator, but her intentions were that of only care. During one pass when Levi was staring a bit too much, Hanji knew she had to do something.
"It's alright, you know." Levi was taken aback, but Hanji was nothing but sincere.
One time isn't the end of the world. Maybe he'll even have something productive to do after expeditions instead of distracting her from the research at hand.
Levi vehemently denied it at first. He did not want Hanji to think that this is a serious thing. Mikasa just... is consistently on his radar. It isn't as if he would ever act on his thoughts, it's bad enough he has them. He wouldn't do that to Hanji. She is more than he deserves, but with Mikasa, it is nothing more than adrenaline fueled lust.
He can't get it out of his mind. This last mission they worked together more than they ever have. Their attacks coordinated seamlessly, and on more than one occasion, they pulled each other out from ridiculously close calls. She was incredible, and so was he.
Pacing around HQ, his blood is still boiling. He needs to burn off this adrenaline, or else he likely won't be productive for a while, just a finicky mess. He continues to try and take menial chores off the hands of his squad, but there is little to be done. He makes his way into the gas and supply room when he sees her cleaning a large pile of 3DMG canisters. His jaw clenches. He knows what he wants, but is more than ready for her to say 'no'. He doesn't even know how to go about this kind of situation. If age and his relationship status was one thing, him being her superior officer is another.
She knows he's there but doesn't look up.
"Can I help you with anything, Captain?" She gives him a quick glance from under her bangs and Levi can feel his face pale.
"No, thank you. Could I help you?" He walks over to the stack and examines the devices.
They belong to the dead. There's no other explanation for the owners to transfer cleaning responsibility to Mikasa. Not bothering to wait for an answer, he picks up a cloth and a filthy device and starts to polish.
"Thank you, Captain." She has little to say, but offers him a maddening smile. The air is as thick as smoke, at least to Levi.
They slowly make their way through the pile without speaking. Deft fingers work fast, and before long, the devices are ready for use again. Dropping her rag, Mikasa looks to Levi.
"Hanji told me about you." Levi freezes. Hanji. Of course she would.
"Yes?" No emotion shows in his face.
"Sir, I'm not sure what to say, but I'm not upset." Relief washes through Levi's mind. Mikasa steps from around the work bench to face Levi.
"But Captain, you should have said something sooner." Hanji, that woman, she told her.
Levi reached out his hand, and Mikasa took it with care. Slowly intertwining fingers, Mikasa pulled herself into him, and Levi responded by crushing her into a forceful kiss. When she responded with equal intensity, he pulled off.
"We need to go. Right now." Mikasa nodded, and they ran up the stairs and down the halls like giddy children to Levi's quarters.
"What about-," Mikasa asked hesitantly as Levi unlocked the door.
"Hanji will be out all night with her lab rat." Mikasa pulled him through the door, and kicked it shut behind her.
It was rough, short, and everything Levi needed. Both taking charge with reckless abandon.
With no remaining duties, they decide to call it a night, and both collapse from sheer exhaustion.
The night is as peaceful as it can be when the nightmares are normal, but the real shock came the next morning when the sleeping pair awoke by being blinded by the sun now streaming through the open windows.
"Good morning! Hope you two slept well, but now there's work to do, and I have to tell you about all I've learned!" Hanji has flung open the shutters, and was met with vocal resistance from the two in bed who never bothered to dress the night before.
Absolutely unperturbed by the scene in front of her, Hanji continues to carry out her morning chores in her room. Mikasa, only slightly embarrassed by the situation, is the first to respond to the wakeup call. She sheepishly redresses, but as she remembers the candid conversation the women shared weeks before, her hesitation washes away and she carries on.
It's obvious that Hanji truly just doesn't mind this situation.
Before Mikasa dashes out the door, she salutes her officers, who haphazardly return the gesture. Levi is barely sitting up in bed, and Hanji is standing next to her desk. She shuts the door behind her.
Hanji shoots a devilish smile to the man sitting up shirtless in bed.
"Was it worth it?" She starts dropping her layers as she saunters over and straddles his hips.
This isn't an OT3 just because I can't see them doing it all together, but Mikasa is definitely Levi's first choice when he's really needing it. Hanji for every other time, not because she is his second choice, but just because she is a busy woman of science who doesn't have time for such trifles. Also, Levi only loves Hanji. He lusts after Mikasa.