There was an unspoken rule among all cells. When one was on duty, everyone had to wear their respective uniforms at all times. Since the cells were actively working in a body that functioned quite well, they were always on the clock, which meant that there was no need to change out of their uniforms. Really, the uniforms were meant to help easily identify what cells were doing what and to make sure that there were no anomalies. Normal cells can attest to the importance of the uniform, that being the incident where some of them had worn funny hats...which actually became some kind of viral invasion.

Regardless, whether you were an erythrocyte, myelocyte, or a basophil, you were supposed to wear your required uniform.

No alterations.

No exceptions.

And so, it came to pass that on one peaceful, but bustling route through the veins, AE-3803 happened to stop for a moment. Since she was traveling through this specific blood vessel, the circuit here was much slower than if one traveled through the arteries. Armed with a cart and carbon dioxide (and notes), it should have been fairly easy to traverse. Except, however, there was a minor setback.

For some odd reason, AE-3803 observed that some of her fellow erythrocytes were scrambling away from a certain direction because of—

"Bacteria! Germs!" A veteran erythrocyte yelled as he brushed past her with a cart filled with carbon dioxide.

At his exclamation, a lightbulb turned on in AE-3803's head before she, too, began scrambling away. Unfortunately, one of her shoes were untied (the main reason why she stopped in the first place) and in her mad dash to escape the incoming monstrosities, she managed to fumble forward and land on her face.

Such an occurrence could be easily remedied by immediately pushing herself off the ground and running, but luck was not on her side. To her utter dismay, one of he invading bacteria had launched one of its appendages towards her. Fearing for the worst, the red blood cell shielded her eyes as if to avoid her fate.

"Well, well, well...a mature red blood cell just ripe for the picking…"

The red blood cell froze before panicking when she realized that while she was still alive, she found herself within the monster's grasp! It's tail, barbed with a piercing tip, had wound tightly around her waist, which constructed her breathing.

"Hey! Get out of here! This body isn't for you to take!"

"Spunk, I like it. It's too bad you're nothing more than a useless red blood—"

Before the invading germ could say another word, a bone white knife embedded itself straight into the germ's cytoplasm. Immediately, the cytoplasm exploded outside of the monster, which completely covered AE-3803's exterior. Whereas she got the majority of the germ's cytoplasm, her savior managed to get off easy.

"Red Blood Cell, are you all right?" Although he was completely bloodthirsty moments ago, he had become the quiet and reserved neutrophil that AE-3803 had come to admire.

Laughing to herself, she took his preferred hand and heaved herself off the ground.

"Ah, it's you! I feel like this body isn't big enough considering that we're always bumping into each other."

At that, the white blood cell's features softened a little—a far cry from his usual stoic expression. Unlike most of his peers, he quite liked collaborating and hanging out with other cell types. The red blood cell, a bit clueless and naive, was still one of the best companions he ever encountered. Not to mention, it was nice idly chatting with someone who wasn't familiar with the mechanics of how the immune cells worked—seriously, he was inclined to agree that most of his brethren were a bit crazed...and weird at times, but they all had their nuclei in the right place.

For the most part.

As the white blood cell was thinking, the erythrocyte began enthusiastically talking about her most recent circuit around the body. Apparently, she had become even more confident in her abilities after her first time and she didn't have to refer to her notes as often! It was such a momentous occasion, the neutrophil was inclined to invite her to stop for a treat at a little resting place to celebrate, but before he could voice his opinion, the receptor on his hat pinged. Instantly, his expression went from relaxed friendliness to that of a killer waiting to encounter his prey.

"Ah! White Blood Cell, duck!"

At AE-3803's warning, the neutrophil immediately completed that action. In doing so, he managed to avoid getting impaled by a barbed tip, but it had knocked off his hat. However, his immediate concern was destroying the bacterium (which, in this circumstance, had realized that it had mistakenly attacked a white blood cell and had run away to seek cover).

"Get back here, you filthy germ!"

"Wait, what about your—"

U-1146's white form managed to disappear without a trace as he migrated between blood vessels.

"— hat?"

Well, now that was unexpected.

What was she going to do with U-1146's hat now?

"Number 1146!" U-2001 called out. Although he often associated with U-1146 enough to be considered friends, they weren't very close. "Where's your hat? How are you going to detect antigens?"

For a moment, the aforementioned neutrophil appeared confused as he absentmindedly patted his head. When his gloved fingers only brushed through the thick strands of his hair, his eyes immediately widened before he spat out the germ he was currently phagocytizing.

With a swear, he jumped up to his feet and addressed his fellow neutrophil brother.

"You wouldn't have seen a female red blood cell toting around my hat, have you?"

U-2001 furrowed his brow.

"You mean the one always getting lost? I haven't seen her during my patrols."

"How am I supposed to do my job if I don't have my hat...The last time I saw her she was in the venous part of her oxygen circuit before—" His eyes widened in an epiphany before he rushed towards the lungs. "Thanks 2001! I think I know where she is!"

As the neutrophil rushed towards his new destination, the other white blood cell shrugged his shoulders before he turned towards the half eaten bacterium.

"Hey! Can I phagocytize the rest of him?"

When there was no discernible response, U-2001 shrugged before he grabbed the bacterium's carcass and began feasting.

"Hmm, since White Blood Cell is an immune cell...and immune cells hang out in the lymph vessels and lymph nodes...then maybe…"

"And what are you doing?"

"Oh, hi!" AE-3803 blushed furiously as she found that her mentor was staring curiously at her—yet, there was an undercurrent of worry and concern lacing her features. "I was about to enter the venous circuit again because I stopped for a quick rest, but I kinda have to make a quick detour because I need to return a white blood cell's hat—"

"A quick detour?" The older red blood cell shook her head before placing her gloved hands to her trainee's shoulders. "Knowing you, you'd probably get lost within the first few minutes. Seeing how capable and intuitive your friend is, I think he knows that you're heading to the lungs."

Aside from the fine dusting of red that came with her flushing face, the young red blood cell didn't know how to react. She knew that the most logical way of going about returning the hat. However, another part of her that was susceptible to emotions and empathy really wanted to see her friend again just so she can make him happy.

Oh, what to do?

"Relax, 3803, you see each other all the time. Just go and do your job."

The erythrocyte sighed before taking her mentor's advice.

After all, they both worked in the blood vessels of one body. It shouldn't take long to find him.

U-2626 may not have had the greatest eyesight (due to his overly long bangs that went against regulation), but even he could see that U-1146 was a bit nervous. Having heard the news from the others, 2626 knew that he had been stripped of his hat, and most importantly, the receptor. Without it, 1146 was essentially deemed useless and had to be partnered with someone who had the proper equipment.

"You okay? You look like you're in a mood."

"I'm fine. Thank you." U-1146 murmured a little tersely.

U-2626 couldn't fault the other for his slightly hostile tone. Most of the neutrophils were hard wired to migrate across the body, they couldn't stay in one spot for a long time. Furthermore, unless one of their kind was going through apoptosis, they didn't like being called out for being "useless".

Not that 2626 agreed.

He thought that U-1146 was still a proper white blood cell. Earlier that day, they had come across an allergen and 1146 went straight for the kill. It was a magnificent display of classic immune response hostility that had 2626 whistling in appreciation. How could anyone call him useless after that?

That didn't stop the hatless neutrophil from being caught in a mood.

"That red blood cell of yours will come. Don't worry about it! You too are like twin progenitor cells from the same bone marrow—totally inseparable."

At that, U-1146 barked a short note of laughter before sobering quickly.

For his sake, U-2626 hoped that the young red blood cell came to the lungs quickly. His friend looked like he was about to go on a rampage.

"Turn left here. Turn right at this valve. Go straight forward twenty steps." AE-3803 mumbled under her breath as she consulted her notes. Normally, she would have relied on her newfound instincts and landmarks, but right now, she wanted to get her route perfectly concise and brief as possible. There was no telling if the white blood cell was going to be waiting at the lungs, but if she were quick about it, then maybe he might be there.

If he wasn't, then she'll have to skip out on one of her deliveries and start searching the lymph tissues. That was the compromise that she planned and one she was willing to work with.

As she turned through one of the corridors that were mostly bereft of most red blood cells, she came across—

"Ah, you're friends with U-1146, right?"

It took a few seconds to register, but the white blood cell who spoke to her was one of her white blood cell's friends. Unlike the other neutrophil, he had a mischievous look in his eyes—eyes that were unaccompanied by any bangs. In fact, his bangs framed the sides of his face, making him appear more approachable and softened his features.

For a moment, AE-3803 imagined what U-1146 would look like if he were to adopt the same hairstyle but immediately blanched at the thought. He would look too...too…

"Adorable." She squeaked out.

"Huh? Miss Red Blood Cell, are you—"

"Hahaha! I guess I'm tired from all my deliveries. Do you happen to know where he is?" She rustled around in her nifty little pack and held out a cap with a receptor. "He left this behind when fighting a bacterium."

At that, U-2048 grinned.

"That's great! I can escort you to the lungs." When the erythrocyte was about to protest, he elaborated. "That's where he's stationed right now."

"Ah, if you're not too busy then suuuuuuuu—"

The neutrophil hoisted her in his arms, making sure that she had grabbed hold of the delivery of carbon dioxide, and took off for the lungs.

Damn, why were the immune cells such weirdos?

"I'd like to fight against a parasite one day."

"That's nice, 2626, but that's an eosinophil's job."

"Yeah, but it'd be cool and it's nice to have a challenge once in a while."

The neutrophil couldn't argue against that, especially since they were basically born to fight, but it was utterly ridiculous for a mere neutrophil to fight against parasites. They could try, but eosinophils were created for a reason.

Just when he was about to reply, there was a slight commotion in frontof them. Curiously, he looked to his partner if his receptor was acting up, but there was nothing amiss. For some odd reason, there was a group of red blood cells scurrying away from…

What the—?

"Mr. Neutrophil, please put me down! There's no need—"

"HAHAHAHAHA!"

U-1146 found himself both relieved and a little—irritated maybe?—offput that his red blood cell was being carried in the arms of his coworker. The feeling of discontent mounted a little when he saw that while the red blood cell was protesting, she did it in a way that suggested she enjoyed it…

His feelings halted when his partner U-2626 waved his arm to get the strange duo's attention.

"Over here, 2048!"

Without even hesitating U-2048 leaped over a couple of unsuspecting red blood cells and in a feat of Herculaneum strength, he—

"2048, don't do that—!"

—threw his precious cargo, erythrocyte and all, directly into U-1146's arms.

The impact was, for the lack of a better term, disastrous.

The package of carbon dioxide went flying, AE-3803's elbows knocked into U-1146's torso, which sent him keeling to the floor, and both of them went tumbling to the ground. What was worse, though, was the landing.

Due to the white blood cell's propensity for protecting others, he had clutched onto the red blood cell as he landed squarely on his back. Unfortunately, that only had him clutching her back and hip to better secure her against his figure. In short…

The red blood cell was lying directly on top of the white blood cell—legs intertwined and her nose in the crook of his neck.

After the excitement of being carried by one of the neutrophils straight from the veins to the lungs, AE-3803 was inclined to just stay in that position and rest. However, reality hit her when she realized that while it was quite comfortable to rest in the neutrophil's arms, it was certainly not the time! She had two items to deliver!

"White Blood Cell!" She broke from his hold (easily, much to her surprise) and rummaged in her pack. "You dropped this!"

She was about to shove the cap back into his head, she saw that his hair looked soft...and eyes looked curiously at her, with adoration and happiness...it was a good look for him, if she was being honest.

"Is there something on my face?"

"Ah, no! I just never saw your other eye before," she hastily mumbled. She flushed darker as his brows furrowed. "But, yeah! Here you go!" And she placed the hat back on his head.

"Ah, thanks, Red Blood Cell." He made as if to sit up from his current position, but stopped momentarily. "Do you mind getting off me?"

If possible, AE-3803 flushed even darker as she realized that she was still sitting on his torso. Hurriedly, she jumped up and pulled the neutrophil back onto his feet. As she did so, she noticed that his hair, once again, covered his right eye. A brief thought came to mind: what were to happen if she were brush bangs to the side without her gloves, to feel the silliness of his locks through her fingers and to see his right eye again…

"I, uh, gotta go! Carbon dioxide still needs to be delivered!" With a parting nod to her escort, U-2048, she took off for the alveoli.

U-1146 was perplexed.

Ever since AE-3803 left, his white blood cell friends were acting dodgy for some odd reason. They would give him sly looks and smirks as they accompanied him on a patrol of the body. As they traversed between the lymphatic tissues and blood vessels, they were joined by their youngest recruit U-4989.

"Hey, guys! Were we assigned to work as a group? I didn't get a memo."

"Oh, no," 2048 smirked, "1146 over here got himself into a little trouble."

2001 added, "He lost his receptor a little while ago."

"And a cute little red blood cell had to help him." 2626 smiled widely.

"Can you believe it," 2048 gasped. "A white blood cell getting help from a red blood cell?" He paused for a moment as he appraised 1146 (who was studiously ignoring the lot of them). "Then again, she was so cute and I liked holding her in my arms…"

U-1146, already used to his colleague's attempts at rankling him, merely brushed their comments aside.

"Well, it's good to have friends from other cells other than us immune ones. Maybe you should try talking to them some time." And with that, the eldest neutrophil strategically dashed away into an alcove.

And no, he was not willing to admit that yes, AE-3803 looked really cute.

Or that he was blushing the entire time they gossiped.

"2048, what was that all about?" 4989 couldn't help but ask. "You shouldn't bother 1146 too much, he might phagocytize you."

2048 snickered in reply as he also left the blood vessel via a hidden passage.

"Don't worry about it, 4989." 2626 soothed. "2048 just happens to like cute things and so does 1146 if what happened today proves anything."

"So what happened?" The youngest neutrophil inquired—albeit, a little crossly.

"He lost his hat." 2001 supplied.

"And?"

"That's it; he lost his hat."

4989 groaned as once again, he was left behind to sort out the pieces.