Or picking the story apart, as it turned out.

Summary: Nathan gets assigned to his new partner, Ellipsia. Polystyrene ensues. Technically, in this story, Nathan didn't get assigned a partner, he arrived at the Response Centre of his new partner. The assigning had already taken place.
Betaed: no

"Ah, this is it." As Nathan arrived at the door to RC#7331, he ran his right hand trough his shortish hair, untousling it a bit. This reads to me as: all the while that Nathan arrived at the door, he ran a hand through his hair. I don't think he did both at the same time. I think he arrived, and then ran a hand through his hair. As, however, means it happened at the same time. Which it can't, because arriving doesn't take a measurable amount of time, while running a hand through one's hair does. Can you tell I am not a fan of using 'as', or '-ing' for that matter, to indicate things happen at the same time. Far too often it is used for things that do not happen at the same time. Be careful of its use. He wanted to make a good first impression with his new partner, wanted to show the professionalism he was renowned for. With one swift motion, he opened the door, So, he wants to make a good impression, but doesn't bother knocking to announce there is a visitor. took a deep breath and stepped in. One step.

"Ohmygod." It took the tall man a while to get out of his stupor. break for new paragraph. The response center was a mess. Mildly speaking. There were boxes standing around, filled with polystyrene balls and/or empty packages from action figures. The figures themselves stood on everything that wasn't declared the floor. Most likely because the latter reminded Nathan of the old children's game "the floor is made of lava". Or because it was already filled with the boxes. Only that in this case the lava was his kryptonite. Even: even more polystyrene balls.I'm a bit confused about what this is about. If the floor is covered with polystyrene would he not have noticed that first and maybe later where all the action figures were? Also, just say the floor was covered with polystyrene. "This... this is ho-" break for new paragraph, because there is a new speaker."Bleeprin's to the left." A head with two brown ponytails emerged from behind a PC monitor, together with a hand that pointed to a sideboard right next to the entrance. break for new paragraph.Nathan turned his head and indeed, there was a whole jar of Bleeprin, together with a half-empty bottle of water for swallowing it. Quickly, he reached over, grabbed one and drank the rest of the water. grabbed one what? a jar or a bottle? "Thanks... so you are..." His brows furrowed. That couldn't be. break for new paragraph, because, again, someone else is speaking."Agent Ellipsia, Elly for short." break for new paragraph.Nathan nodded, waiting for the Bleeprin to kick in.

Meanwhile, Ellipsia disappeared behind her screen again, hammering onto the keyboard furiously. "ARGH! Of course you get agro when you use that spellcomma you moron!" She laid her lower arm onto the desk in front of the keyboard and started hitting her head against it. break for new paragraph. Nathan raised an eyebrow. Slowly, he stakedwrong word. Stake is to support with stakes, or to (aggressively) claim something (like territory) for yourself. I don't think Nathan is doing either. trough the sea of polystyrene, trying to stay calm at the sound it made, until he stood behind her desk. "So let me guess... Warcraft." break for new paragraph."No, I'm sooo into Twilight. Of course!" She gestured at the screen. break for new paragraph.Nathan sighed. "Fun time... oh, and you just died." break for new paragraph.Her head dropped again. "It's these groups that make me wish for a mission." Having grown frustrated enough, she hit Alt-F4 and stood up from her chair. break for new paragraph.To Nathan's surprise, she was almost as tall as him. break for new paragraph.The woman breathed in, smiled and stretched her hand out to him. "Okay, for real this time. I'm Elly, and you are..." break for new paragraph."Nathan. Just Nathan." He shook her hand firmly, nodding to it. break for new paragraph."So you're my partner. Feel like you're at home." break for new paragraph."My home doesn't include... these." The man shivered when he looked down to the box filling on the ground, which made Elly giggle. break for new paragraph."Oh, you're one of these guys." break for new paragraph.The man straightened his clothes. "I just like my place to be clean." With these words, he walked over to a second desk which was yet another storage place for huge boxes. Fortunately, they were empty, so Nathan could pick them up one by one and place them somewhere else. "What are you doing with all these boxes? I mean why are you keeping them?" break for new paragraph.Elly grinned. "I like ball pools." break for new paragraph."YouWe'll need a new jar of Bleeprin. Soon."