Posted originally on the Archive_of_Our_Own at https://archiveofourown.org/
works/938673.
  Rating:
      Explicit
  Archive Warning:
      Underage
  Category:
      M/M
  Fandom:
      Shingeki_no_Kyojin_|_Attack_on_Titan
  Relationship:
      Armin_Arlert_&_Eren_Yeager
  Character:
      Armin_Arlert, Eren_Yeager, Titan!Eren_-_Character
  Additional Tags:
      Macrophilia, Hand_Jobs, Hand_&_Finger_Kink
  Stats:
      Published: 2013-08-23 Words: 1370
****** Independent Variable ******
by animehead
Summary
     In which Armin loosely relies on the Scientific Method.
The first time it happens, they’re still too young to fully understand it. Of
course, that was years ago and now they know exactly what they’re doing. 
The problem is they never speak about it afterwards. 
It’s not that Armin hasn’t tried talking about it with him in the past. But
Eren always finds a reason to excuse himself, always comes up with a way to
avoid speaking about the things they do to each other when no one else is
watching. 
Eventually, Armin decides that talking about is pretty much improbable. Eren
has never been the type to communicate as freely as others. In fact, sometimes
Armin thinks that simple conversations are sometimes too stressful for Eren and
the last thing that his best friend needs is more stress. 
Eren doesn’t handle stress very well. 
The burning sting of a cut on his left shoulder pulls Armin away from his
musings, and he silently scolds himself for forgetting the dangers of the world
around him for something that almost anyone else would deem trivial. 
He’s not too badly injured, thanks to Eren. Honestly, it annoys Armin how often
that seems to happen. He’s still not pulling his weight like everyone else and
it makes him feel useless, regardless of how intelligent everyone seems to
think he is. 
Armin winces when he grips the shoulder of his jacket and pulls it away from
his skin. The blood soaked fabric of his shirt clings to the fresh wound,
making him clench his teeth in pain. 
A loud huff of breath comes from high above his head and Armin doesn’t need to
look up to know that Eren is staring down at him, concerned for his well-being
as always. 
“I’m fine,” Armin says. “It just stings a little.”
Eren narrows his eyes and Armin can’t tell if it’s out of disbelief or genuine
concern, but when one of those giant sized fingers points in the vicinity of
his shoulder, Armin assumes it’s a little of both. 
Armin doesn’t say anything when he gently slides his jacket halfway down his
shoulder and tugs at his shirt collar. He shows off his battle wound to Eren
with something akin to pride before, without warning, Eren picks him up. 
Eren holds Armin in the palm of his hand, his entire body eye level with Eren’s
glowing green eyes. Armin can’t help but think how so many people would be
terrified to be this close to a titan’s mouth and yet, he isn’t the least bit
afraid. 
Armin finds himself taking in the sight of Eren in his titan form— rows of
dangerous teeth and pointy ears not unlike the fictional elves he’s read in
fairytales and fables when he was much younger. 
Armin laughs at that thought, and when Eren brings head closer toward Armin as
if asking Armin what’s so funny, Armin laughs even harder. 
When he stops laughing at the notion of titan elf Eren—and the ridiculousness
of such as all the elves he’s ever read about have been smaller than most
humans—Armin lowers himself onto Eren’s middle finger and smiles. 
He wishes that Eren would be more willing to communicate with him when it comes
to certain things. He doesn’t want to complicate things with Eren, but he does
want to know if what they’ve done means anything to him. 
No, that’s a ridiculous question. Of course it means something to Eren. It has
to. They’re best friends and Eren has never done anything remotely sexual with
anyone else. 
Or… has he?
Armin could ask Eren that. He could ask him right now, actually, but he knows
he won’t get a proper answer or even one that he can even understand. But he’s
given it some thought and he’s noticed a pattern between him and Eren. 
Whenever they do… things, Eren is always the one to initiate it. Gentle brushes
of his fingers beneath Armin’s ear as he’s walking past, late night kisses that
leads to warm hands slipping inside his pajama bottoms… and it always happens
whenever Eren has spent any part of the day in his titan form. 
Which means that he can fully expect him and Eren to do something later today. 
But what if Armin changed it up? What if he was the one to actually initiate
things? What if he became the independent variable? What if it resulted in Eren
actually wanting to talk about their friendship, about their relationship?
He admits to himself that it isn’t very likely. But he would have thought Eren
being a titan also wasn’t very likely, so it was worth a shot, right?
Armin knows he’s blushing when he unfastens the lower half of his clothing, but
he doesn’t really care. Eren seems confused, as usual, but Armin doesn’t waste
any time explaining things to him. Both his ears and cheeks burn with
embarrassment by the time he’s fully exposed, his cock rigid and mere inches
above Eren’s palm. 
Armin watches Eren and his struggle to either stare into Armin’s eyes or to
keep his gaze down. He’s always secretly wondered if Eren could ever get
aroused as a titan, perhaps not physically since he lacked any sex organs in
his titan form, but maybe it was a mental thing? Then again, whenever Eren was
in his titan form he was usually killing titans and Armin doubted something
like that would turn Eren on. 
But then again…
When he widens his legs, Armin’s thankful for his natural flexibility and the
fact that he rides horses, otherwise spreading his thighs far enough apart that
his cock grazes Eren’s skin would have been more painful than pleasurable. 
Armin chances another glance at Eren, but Eren’s eyes are focused on his hand,
watching intensely as Armin rocks his hips back and forth, gliding his cock
against Eren’s huge finger. 
A moan slips from Armin’s lips and Eren growls low in his chest in return.
Armin tries his best to watch Eren, but eventually his glazed blue eyes shift
downward and flutter close. He leans forward, hands clutching at Eren’s fingers
as he grinds down, the friction from Eren’s skin making him gasp and drop his
head forward. 
He’s too busy enjoying the sensations of Eren’s finger gliding across the tip
of his cock to notice the desperate and longing expression on Eren’s face. 
“E-Eren,” Armin moans, just as Eren uses the index finger of his free hand to
tilt Armin’s chin back, forcing him to meet Eren’s gaze. 
Armin cries out after that, cumming while whimpering a gasped and broken
version of Eren’s name. He shudders, thighs quivering from the intensity of his
orgasm. It’s too much for him to speak, so he just gazes into Eren’s eyes and
hopes he understands. 
When his hips no longer seem to want to thrust violently against Eren’s hand,
Armin finds the energy to tuck himself back into his pants and refastens his
clothing. 
“We should probably head back now,” he says. “It looks like everything is all
clear and the longer you stay in your titan form, the longer it takes you to
recover.”
Eren just stares at him, as if expecting Armin to explain what that was or why
it happened, but Armin says nothing. He even pretends not to notice when Eren
licks his finger and wipes it on a nearby tree after he’s moved Armin from his
hand to his shoulder. 
It’s much later that evening when Armin is sitting outside admiring fireflies
during a brief moment of peace from noisy comrades and murderous titans. He
hears footsteps approaching him and isn’t at all surprised when Eren lowers
himself into the empty space next to him. 
“How are you feeling?” Armin asks him, but Eren doesn’t answer him. 
Instead, he hooks his pinky finger with Armin’s and stares down at his now
average sized feet. 
“I… um…” Eren hesitates, but Armin doesn’t push him. “About today…”
“We don’t have to talk about it,” Armin says. And he actually does mean it. 
“I want to talk about it, about us,” he adds softly, his voice barely above a
whisper. 
And Armin holds back a smile and nods because he figured Eren would.
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