To the guest reviewer who commented that being alone would be less dangerous to Abathur than having friends: he doesn't know that. Also, if you review signed in, I can actually respond to you more directly.

Disclaimer: No actual science is here. Except the science that allows you to load up the page and see it around the world. That's science. In the story, however, there is none. Also, don't own the stuff.

(If you wear glasses, I highly recommend transition lenses. They are very useful)

Catalyst

Abathur didn't really understand Halloween, or for that matter, any human holiday. Why bother consuming extra food, and putting up random scraps at one's dwelling on a particular day? It wasn't any different from another, aside from the obvious temperature and meteorological variations. Some of them, from what he understood, functioned as methods of remembering significant events, which Abathur supposed was understandable, given the terrans flaws in memory. But some, such as the aforementioned Halloween, were simply baffling. From what he had managed to pick up, it was something about spirits, monsters, and pumpkins. What relations they had to each other, much less terrans as a whole, was beyond comprehension.

Still, they each had their upsides. Halloween, it seemed, had a feast of food, which was far from unwelcome. Abathur was running through biomass as fast as the school provided, all the changes he was making needed energy, so he was taking advantage of the feast to take in as much of it as he could, as fast as he could. He noticed some stares from the other Slytherins seated nearby, but ignored them. They hadn't done anything when he'd done it before. Not to mention, the bigger, lower intelligence one's a bit to his left were doing it too.

Abathur had had much less productive time periods. Of course, he had also had more productive ones, but no opportunities were preventing themselves for anything better than stocking up on biomass. That is until the terran with the annoying speech defect came running into the hall, disheveled, distressed, and screaming at an unpleasant volume.

"Troll! In the dungeons!" He screeched. At a lower volume, he added. "Just thought you ought to know." The terran then collapsed promptly. Abathur continued to eat. Noting the others' lack of attention, he also took the opportunity to grab a partially burned gluten structure from in front of the blonde one. What were trolls again? Abathur vaguely remembered reading about them. Weren't they those large humanoid mammals with moderately greater strength and thick skin? Certainly something worth investigating, if not necessarily collecting.

Abathur finished his plate, taking a last bite of the gluten structure, then stood. He looked around at the chaos from the other students, watching them panic as the teachers and prefects desperately tried to impose some semblance of order. It was certainly a scenario that would make it easy to slip away, ideal for his purposes. The only thing left was to actually find the thing, and make his way to it. If Abathur was still with the swarm, he could have bounced his mind through tens of thousands of eyes, ears, and minds, seeing, hearing, and knowing all. As he was, all he could do was work with the sensory organs he had, and his own, still underdeveloped psionic senses. It would have to do. Ignoring the mad scrambles of the terrans, Abathur made his way through the crowds, exiting the decently sized hall.

Abathur listened intently as he wandered the corridors, listening, hopefully, for grunting, heavy footsteps, perhaps random snapping sounds. As such, he was quite surprised to hear not only grunting, footsteps, snapping, and smashing, but the screams and shouts of younger terrans. Abathur broke out into a run, rounding a corner to find three children fighting the troll. Or at least, the assumed troll, although the castle didn't have a particularly wide selection of large, oddly tinted bipeds with large clubs. Well, not oddly tinted ones anyway. The terran-giant hybrid covered the other categories.

Abathur ran at the fight, attempting to get to the troll before the others damaged it beyond study, managing to reach it right when the troll was beginning a swing towards the red-haired one. Abathur leapt into the air, pulling back his arm. Right before he would have contacted the troll, he pushed the limb forward, striking the troll directly in the ear. A strike like that from a full zerg would have killed the troll then and there, either snapping its spine, or simply cutting through the skull into the brain. A blow from a terran would have barely drawn its attention. Abathur's blow staggered the troll, causing it to lurch a few steps, and interrupting its swing. In retaliation, the troll swung its club back at Abathur. Abathur managed to bring his arm up to block the swing, for what little good he did. When the club made contact, there was a sickening crack, and Abathur himself was flung backwards, flying into a wall, before sliding down onto the floor in a heap.

"Bloody hell!" exclaimed the troll's intended victim, before gulping as the troll's attention turned back to him. The troll and the three other terrans were soon drawn back into conflict, with no notice able to be afforded to the evolution master. Abathur lay meekly, dazed and in pain. With considerable effort, he drew himself upright, blocking the repetitive pain signals, and reorienting neurons to better adapt to the collision and fixing other, similar issues as much as he could. Facilities regained, Abathur looked down at his right arm. It was lying limp against his side, angled unnaturally at the fore and upper arm. With a deeper look, he could sense four distinct breaks along the limb, along with innumerous cracks.

Without healing, this would be a significant detriment to Abathur. Either he turn himself over to the terran medics, which would likely result in discovery, or... well, he hadn't tried that for well over a decade, since before he... transferred. But with the terrans still trying, only somewhat successfully, to fight the troll, he only had so much time before his life was at risk. There was no other option. Abathur closed his eyes and concentrated. He gathered his power, condensing it slightly to the right of the center of his form. Then, with a push of intent, he released it. His energy flowed through his body, encasing and penetrating every cell, illuminating the area with a orange-pink glow. His arm snapped back into place, the bone sealing itself along the muscle with perfect precision, the tissue and vessels following suit. With the excess energy from the burst, he wove intricate structures beneath his skin, insect inspired carapace and armor, hidden from view. With a green tint in his eyes, Abathur stood, successfully Mended, and ready to engage in combat once more.

Abathur snuck around the troll, making sure to avoid its attention while it tried to pummel the humans. From the looks of it, they surprisingly weren't dead yet, and actually might have managed to survive without Abathur's aid. But that would result in loss of essence, an unacceptable outcome. When he had reached the troll's back, Abathur reached up and grabbed it's shoulder, flexing the muscles in his palm to push the jellyfish derived barbs into its unsuspecting flesh. Then he did it again. Both times, the troll barely noticed, the harpoon-like structures barely penetrating into its thick skin. The troll reared around, prepared to smack the interloper away again, but was distracted by its own club moved into its face by the black-haired terran, and a stick shoved up its nose by the red-haired one.

Abathur stepped back and appraised the threat. If his barbs weren't enough to penetrate the skin, he needed something better. Gathering the remaining energy from the Mend, he moved it to the underdeveloped plates at the tips of his fingers, flowing it through sequences contained, but not yet expressed. Soon the nails grew to many times their previous length, tipped with a blade that would be more appropriate on a hawk than a terran. With the troll still distracted, Abathur thrust his hand forward with a scream, thrusting it palm deep in the troll's flesh. With no armor blocking the barbs, Abathur flexed his hand once more. A toxic mix of dozens of venoms was injected into the troll. Its eyes registered surprise, then pain, then they turned dull and lifeless. With a last gasp the troll fell forward and lay still, leaving the terrans and Abathur standing around its corpse, panting.

"What the bloody hell just happened?" said the red-haired one.

"I think we just won, Ron," said the one with the facial disfigurement.

"Alright, but where in Merlin's name did he come from?" The now-named Ron pointed at Abathur accusingly.

Well, this was bad. He hadn't anticipated others also trying to engage the troll. In an effort to hide, he put his hands behind his back, and began chemically eating away at his nails, hoping to trim them before they noticed.

"Was seeking to return to quarters. Lost path. Encountered you. Sought to help." Lying was not something Abathur was accustomed to. Most of the time, there was no need for it. But this would have to do. Fortunately, he was spared having to continue by the arrival of various teachers.

"What is going on here?" McGonagall demanded. All of them simply stood in silence for a second, before the longer haired younger terran stepped forward.

"It's my fault professor," she said. "I read about trolls in a book, and thought I could deal with it. Ron and Harry only came to help me out. And he," She looked over at Abathur. "Actually, I don't know your name."

"Abathur."

"Abathur here got lost trying to get back to his dorm, ran into us, and helped us take it down," she said.

McGonagall stared disapprovingly at the quartet. "Taking on a troll is a very, very dangerous thing to do. 1p points each from Gryffindor, and 10 from Slytherin as well. Now, are any of you hurt?"

"I think Abathur got punched into a wall," The black haired one said.

"Did not occur. Am healthy. No attention required," Abathur said.

"Alright then. If everyone is okay, you may return to your dorms. And make sure to tell a teacher where you are going next time," McGonagall said.

With that the group began to disperse. Abathur moved to split away and return to his dorm. He was interrupted by the black haired one. "Hey, Abathur. Want to walk back with us?"

Abathur wasn't sure how to react. Fortunately, Ron did it for him. "Harry, mate, could I talk to you for a second?" Ron took Harry aside, and while Abathur couldn't hear most of the conversation, he did catch a few words.

"...a snake, Harry, a Slytherin!"

"...troll was swinging at you..."

"...just plain weird..."

"...that about Hermione, too..."

Eventually the pair separated and turned back to Abathur. "Alright, I guess, you can come with us if you want," Ron said. Abathur was about to refuse, until he remembered Dumbledore. The elder terran was in a position of great power, and if he discovered Abathur, that would be a nightmare scenario. And he was already on thin ground with the friend debate. Perhaps, if he used the terrans as camouflage, it would avoid additional attention.

"Acceptable," said Abathur. He walked over to the terrans, and as a group, they began walking down the corridor. After all, Abathur reasoned, it wasn't as if these terrans were particularly dangerous, or in a good enough position in their society to make any massive attack. Should they attack him, Abathur thought as he licked the troll blood from his hand and noting the sequences, they shouldn't be too hard to eliminate.

Roach: One of the most commonly deployed zerg forces, roaches are fairly durable acid spitting creatures, one of the swarms most versatile ground units. Roaches somewhat resemble beetles, with a large, round shell, topped with two scythe-like blades. The roaches main attack is launching an acid spray towards their foes, dealing moderate damage. Roaches also possess the rare ability to move while burrowed, an ability shared only with the Infestor, and some variants of the Swarm Host. This allows them to sneak into areas normally very difficult to approach, and launch a surprise attack. While burrowed, Roaches also heal at an extremely rapid rate, allowing a skilled controller to make them last far beyond the normal limits of their health. Roaches also possess the ability to morph into the bile spitting Ravager.