To Jean, Armin was fairly easy to read most of the time, despite his restraint.
This was a skill Jean acquired from the years of knowing and befriending, to eventually dating him. Armin wasn't willing to allow most of his friends and family to enter his personal space, thus accessing his inner thoughts and unrevealed secrets. He acted as a natural confidant.
Eren and Mikasa, his childhood best friends, were still met with wariness if Armin needed to divulge. Being the blabber mouth he is, Eren was never trusted with Armin's vital information while Mikasa's small, black eyes bore into Armin so intensely that her deadpan stare heightened his emotional state. Genuine care evident in their cajoling so Armin was grateful for their presence.
Jean, however, operated differently, which put him in a trustworthy spotlight in Armin's mind. He understood how Armin composed his muddled up feelings and emotions before gaining enough courage to approach Jean with coherent speech and how to deal with his issues in the comforting, non-judgmental attitude Armin appreciated every single time. Internally, there was an air of smugness that Jean radiated when he thought about this.
His insecurities often bested him, particularly when Armin would revert back into his shell, leading Jean to ponder how much Armin truly didn't mind confiding in him. Was Jean unknowingly forcing Armin? Or was Armin withholding various intimate secrets about himself? It's okay to keep certain secrets about yourself in a healthy, loving relationship, isn't it? Though their communication skills were mature for their age, Jean felt exposing his worries to him would incite more harm than resolution.
Sporadic periods of Armin's insomnia would often alleviate these insecurities. Jean became clueless, helpless and upset simultaneously when he recognized his symptoms beginning once more. As a testament to Armin's will (and stubborn mental health), he never slept anywhere except for his own bed. Eren and Mikasa, with their usual aggressive, albeit worrisome, approach of forcing the blonde to rest at their house never succeeded, disappointingly enough.
Armin would never accept the offer to nap at Jean's house no matter how severe his sleep deprivation became. After a while, Jean learnt the rare, sleepless periods occurred when he was under extreme stress which was unhelpfully exacerbated by his poor and strenuous studying habits. Adopting Eren and Mikasa's overbearing route would cause Armin to feel uncomfortable, so Jean never pushed him. Still, it hurt a little, as Jean interpreted his reluctance to sleep as a sign of mistrust towards him. You are at your most vulnerable state while sleeping, after all. However, it made sense to hold the primal sense of vulnerability for a small moment to avoid sleep in the presence of others except for your own boyfriend, right? These were the insecurities Jean kept suppressed at risk of making Armin uncomfortable.
But, Jean didn't have to keep his thoughts to himself for long. On a warm, lazy Friday afternoon, Jean discovered Armin had fallen asleep on his couch after the brunette boy had left the room for less than 5 minutes.
"Jesus..." Jean mumbled quietly while he tiptoed towards his sleeping boyfriend. Armin's limbs sloppily draped off the front of the couch with his body was gently slumped against and cradled by the cushions underneath him. That position couldn't possibly be comfortable, but Jean was hesitant to move him in case he accidentally roused him. It was humbling, Jean decided with light delight as he cupped his serene face and ran a slow thumb over the tenebrous under eyes, to see Armin in this rare state. Attempting to wake him would be foolish; the exhausted blonde deserved to sleep properly.
He spread a thin blanket over him with the utmost care in mind before settling on the couch next to Armin. Jean resolved to wait for him to wake up while keeping him company in a protective, albeit inwardly assuaged, manner. Taking advantage of his unconscious state allowed Jean the freedom to touch Armin (innocently, of course) with reassurance and comfort through his hair or along his face. God, it was difficult to retain focus on his homework without the impulse to wrap his whole body around Armin and squeeze him happily.
Unconsciously, Armin must have sensed Jean's presence next to him. Jean found that every movement Armin made unpremeditated in his sleep served to gravitate towards Jean. He was incredibly lucky, Jean decided as a mawkish smile spread over his face upon watching the sleeping boy snuggle deeply into him and lock his arms firmly around his hips, to be privileged enough to witness Armin in this state.
Armin only slept for an hour or two before very slowly regaining consciousness. He frowned drowsily at the practiced fingers drawing a familiar route through his hair. Whoever was doing that was distracting him, but man, Armin couldn't deny how it felt so good...
"Mhh...?" The previously sleeping Armin struggled to lift his head from Jean lap groggily.
Jean's helping hand carefully situated itself under Armin's jaw to help him tilt his heavy-feeling head. He couldn't stifle his smile upon gazing into Armin's disoriented, blue eyes. Those same eyes recovered slowly after studying Jean's face to quickly flash momentary horror, realizing his current position. "O-Oh, I'm sorry-"
"It's fine," Jean interrupted Armin softly to assure him. "I don't mind; you're obviously exhausted."
As if still deciphering the brunette's assuring words, Armin continued to blink slowly while staring at him. Jean was almost convinced Armin appeared to be dozing off once more from the lack of response and tempted to gently shake him to continue the conversation.
"Are you sure?" Armin questioned, but already took the liberty of sinking back down onto Jean's lap without waiting for a response.
"Definitely. I'll wake you in a few hours if you'd like, okay?" He tilted his head to observe Armin's expression at his offer. Instead, his blue eyes hid behind his eyelids as he settled to sleep again.
"Okay...if you really don't mind," Armin mumbled. Jean couldn't see it, but he knew the blanket he'd pulled up to his nose in an attempt to find a comfortable position hid a faint smile.
Jean's pale brown eyes softened as he resumed his fingers' original paths on Armin's scalp, selfishly glad that Armin wasn't open enough with anybody else for them to witness this. And, Jean decided as he listened to the telltale steady breathing from the already dozing Armin, he was stupid for allowing himself to believe that Armin distrusted him in the first place.