Children you call them? They can pull a trigger just as well as veterans, and they have the spirit of a bull narthax. Call them children if you wish - I call them troops.

-Colonel Marus Cullen, Pannonia 5th Infantry Regiment on Whiteshields

They have come to destroy you.

This statement, while it seems terrible and impossible to the ignorant, to those who know of the Imperium of Man, it comes as no surprise.

You see, in the Imperium of Man, we've seen many different types of aliens, and all are evil, murdering, scumbags. You've got the sinister, degenerate Eldar, the berserker Orks, the insidious Tau, the mindless hordes of the Tyranids, and the machine-like Necrons. Most of my experience was with the Orks.

Now, they'll tell you that the orks are weak, that they're cowardly, that their bones are brittle and snap easily, but I can tell you this; they are nothing of the sort. They're stronger than a grown man. They'll fight for fun, and they never retreat. They are much more powerful than a human and if it was a fair fight, they'd have conquered us. If it was a fair fight.

But we humans are far more intelligent than them. We can plan, we can strategise, we can use tactics. Thats what separates us from the xenos, from the aliens. We are BETTER than them. This we know.

But the Yeerks were unlike any alien we've ever faced. Sure, the Eldar will trick you. But these Yeerks would... Well, I'll get into that later. You don't have long to wait.

They are called Yeerks. They are different from us. Different from you, as well.

I snorted at this statement.

"Of course they are different from us! We humans are pure, sacred. We are BETTER than you scum." I proclaimed. At this, the alien stared into my eyes, and I realised that, despite its injuries, it was still full of hate and envy. It had good reason. After all, what alien would NOT want to be human? It was jealous of my humanity.

Many are here. the alien told us.

This was depressing, to say the least. Many aliens here? Could they have already landed a suitable invasion force? My feelings were squarely soothed by the xenos' next statement.

Hundreds. Maybe more.

How could such an insignificant number pose any threat at all? I've been in battles between thousands, tens of thousands, hundreds of thousands, even millions. If the number is barely in the hundreds, how could they be any harm?

Of course, the civilians, being unexperienced in the ways of war, thought this was a large number indeed, with one of the boys, not the possible leader, but one of the other two, asking "Why hasn't anybody noticed them? I think someone would have mentioned it at school."

Suddenly it clicked.

My brain, filled with at least some basic knowledge on the pre-Imperium languages, recognised this strange one, 'school'. I knew what it meant. And I knew what that meant for us.

School, the pre-Imperium version of the Scholae. Archaic now, and only known as a curiosity.

This meant one thing.

We had travelled in time.

Don't ask me to explain the Warp, because I can't. Don't ask me to explain Warp travel, because once again, I can't. All I know is that the Warp is the home of Chaos, and like Chaos, it is unpredictable. Fast routes become slow. Time itself is changed. The best analogy, I think, is from Space Lanes of The Imperium and the Perils of the Galaxy, from Volume 1, chapter 1, which reads:

"Consider, dear reader, this metaphor to explain how travelling through Warp space works; that of a fast flowing stream. The stream represents Warp space moving swiftly along its motionless banks, which represent real space. A corpse dropped into the water upstream will not move relative to the water, but is merely carried by it until it lodges at some point downstream from its original location."

We were on Holy Terra, that was certain. When we were, however, was much less sure.

But that didn't matter.

We were humans. We would deny the alien, the mutant, the heretic.

This alien seemed to know what we were thinking, for he said

You do not understand. Yeerks are different. They have no body, like yours or mine. They live in the bodies of other species. They are . . .

As I've said before, nothing really prepares you for your first psyker message. This is multiplied a thousand-fold when it involves pictures. When something bursts into your brain, bypassing the conduits from the eyes, it can send even the bravest men to their knees, wetting themselves in primal terror.

These humans won my respect in that, at least.

The image that the alien had placed in my mind was different to every other alien I'd seen. It was in the form of a slug, glistening and writhing.

The image broke as one of the teens, the same one that spoke last if I remember correctly, who I now know as Marco, spoke again.

"I'm guessing that was a Yeerk." he said. "Either that, or a very big wad of slimy chewing gum."

They are almost powerless without hosts. They - the alien cut off, and a spurt of pain flooded through.

I guess I'm used to the feeling of psyker magic, or maybe the Emperor still protects here, but I could endure it easily.

The kids could feel it, though, and they seemed to be more affected. But I digress. This isn't really important to the story, just a bit of trivia.

The Yeerks are parasites. They must have a host to live in. In this form they are known as Controllers. They enter the brain and are absorbed into it, taking over the host's thoughts and feelings. They try to get the host to accept them voluntarily. It is easier that way. Otherwise the host may be able to resist, at least a little. continued the xenos.

This was pretty mindblowing, as you might guess. These other xenos could take over a human's brain? They could hide and would never be noticed. All that could prevent an epidemic would be the Inquisition, and even they might be fooled by some of them.

It would be critical to the Imperium that I, whenever this is, find a way of stopping this take over, or detecting it, and then leaving it somewhere for the future generations. Only then could I not have failed. With that information, Humanity would be safeguarded from another group of treacherous aliens. They would be unable to hide themselves.

I had my goal, at last. For better or for worse. Whether I lived or died. I knew what I would do from now on.