My name is Tom. The Yeerk in my head is named Tem.

A lot of things changed in my life after I invited Tem to live inside my brain. My life changed in strange ways. But perhaps the strangest thing of all is that I adjusted to it so easily.

Symbiosis was like having a close friend follow me around - ALL THE TIME. Literally twenty-four hours a day. Tem was with me while I had dinner with my family, not that they knew it. He was with me when I watched TV, did homework, worked out, brushed my teeth, showered and used the bathroom. Sometimes he offered commentary, and sometimes he just observed silently. While I was getting used to him, he was getting used to the entire planet Earth.

And, yeah, that much closeness was awkward and annoying at first. But only at first. Once I adjusted to it, it felt completely natural to share my body and thoughts with him. It might have been because he wasn't human. Stuff like this really was natural for symbionts. Also, Tem learned literally everything about me right when we first met. There was no point in acting shy around someone after that. I could understand how most people would hate being a host, but the lack of privacy didn't really bother me.

One exception: I stopped masturbating. I didn't even fantasize about girls anymore. Yeerks think using hosts for stuff like that is vulgar. Tem saw all my memories of me doing it - there was no helping that. But he had zero interest in watching it live. And even if he was interested, that was the one thing I refused to do with an audience in my head.

But in most other ways, having him around was fun. I enjoyed feeling his excitement at experiencing this new world. Sights and sounds and legs and fingers were all new to him. He understood it all thanks to my memories. Tem "remembered" listening to music, playing sports, and eating candy, but he never actually did those things himself before. He was eager to try it all firsthand, and I was happy to indulge him.

And because I could feel Tem's emotions, it was like the reaction to everything my body did was doubled. When I drank a glass of soda, it was like I was tasting the sugar for the very first time - because half of me was. I couldn't believe how sweet and cold it was. And the bubbles tickling my nose almost overwhelmed me! I had to stop drinking as I burst out giggling.

My mom noticed. I cleared my throat and said, "I-I remembered something funny. It - You had to be there." She accepted it and moved on.

As far as I could tell, my family didn't suspect anything. How could they? I wasn't any different on the outside. I was just quieter and more introspective. "Lost in my head" as they might say, having no idea how accurate that was.

My family thought I was the same, but there was a lot different in my life. The most important difference was the Three Day Rule.

Humans get their energy from food, water, and oxygen. Yeerks get theirs from Kandrona rays. A Kandrona is like a small power station attached to a Yeerk pool, filling the liquid with an energy that imitates the sunlight of their home planet. Yeerks need to leave their host and return to the pool in order to feed. While humans can go without food for varying amounts of time, Yeerks have a strict time limit of three days. If they ever go longer than that between feedings, they die.

And the only Yeerk pool and Kandrona we had at the moment was inside the ship in the woods. No matter what else was going on in my life, I had to manage my schedule in order to drive out there every three days.

Tem first entered my brain mid-day Saturday. Three days later would have been during school on Tuesday, so we returned to the ship Monday evening instead. Tem slipped out of my ear and back into the pool. For about half an hour, I was alone again for what would be the only time for the next three days.

I decided to lock myself in the ship's bathroom, once I made sure no one could hear me. (I'm a healthy teenage boy - don't judge me.)

It didn't hurt for Tem to exit and reenter my head. It hurt like Hell the first time, because Tem had to break past my eardrum and my skull itself - the human ear canal simply did not evolve with Yeerk passage in mind. But the slime on Tem's body acted like a painkiller, and it left behind a sort of mucus-y membrane in the spots he damaged. Those membranes filled the hole in my skull and did most of the work of my eardrum, and Tem could brush them aside like flaps without breaking them. Yeerk passage was now easy and painless - for my right ear, at least.

For Tem's small size, damaged DNA and many weaknesses, his body was capable of incredible things. I was amazed.

Another change to my life was the way my grades improved. Which was great, since that was the reason I went to the Sharing in the first place. But they didn't improve that much. Tem knew all about z-space and Sario rips and how gravity really worked, but he didn't have the "wrong" answers my primitive human teacher was asking for. And not having been born on this planet, he didn't know any more about Earth history or human biology than I did. We still had to study a lot.

Tem didn't like studying. He loved doing it back in the pool, but now that he was out, he'd rather be doing stuff. Of course, it's not like I enjoyed studying either. I just had to. And since Tem read all the same books that I did, once in a while he would remember something I forgot - or vice versa. Two sets of memory for the price of one. So my test scores improved a little. Just enough so I didn't have to worry about the dumb jock stereotype as much as I used to.

The biggest improvement was math, since that was universal and Tem was a genius. I actually started to give wrong answers on purpose. If my math scores suddenly went from "C's" to straight "A's" overnight, people might think I was cheating.

And for the record, I do not consider any of this cheating. Tem was a part of me now. Our thoughts and memories bled into each other without even trying. I couldn't just "shut off" that whenever I did homework.

Mr. Tidwell, the host for Illim and the hardest teacher in my school, didn't really approve of me getting help from Tem. Being a host himself he understood, but he still didn't like it.

"It's not like we're trying to cheat," I defended myself against him. "Tem tries to hold back his help in math, you know."

"Only to stop people from getting suspicious," Tidwell replied.

"It still counts!" I shot back. "What am I supposed to do? Leave Tem in the pool, all day, every school day?"

[Please don't put that idea in their minds,] Tem pleaded.

Tidwell and Illim knew there was nothing they could really do about it. In the end, they let it go. But they made a point of not taking it easy on me in English class.

Tem and I were a pair. For the most part, I controlled my own body. Tem could forcibly take control for a second, or blurt something out of my mouth if he was excited, but he couldn't have real control unless I relaxed and allowed him to work.

He wanted practice with my arms. He wanted to have fun with sports. So I lay face up on my bed holding a basketball. I relaxed. I waited for my arms to start moving.

Tem threw the ball up in the air, not quite high enough to hit the ceiling. As it fell back down, my hands tried to catch it, but fumbled. The basketball hit me right in the face and bounced onto the floor.

"Uh . . . Ow," I said pointedly.

[Yeah, I know. I felt it too,] he thought irritably.

I grabbed the ball and returned to the bed. Tem tried it again, and he caught the ball this time. And the next time. Tem played catch with himself, throwing the ball up and catching it. Tem had very little experience moving a host body, but he had all of my muscle memory to make it easier.

For me, it was kind of exhilarating. I kept watching the ball coming towards my face, worried it would hit me again, struggled not to react, and then at the last moment my hands always caught it, without any input from me. It was scary and fun.

I lived my whole life controlling my own body. But now my arms and hands were playing ball all on their own. It was like strings I couldn't see or feel were moving my body around. It was so weird.

I loved the weird. I loved the new.

[Tom, I need to stop,] Tem told me after several minutes. [I'm getting tired.]

[Okay.]

I retook control and rested the ball on my chest. I could have gotten up and done something else if I wanted, but I chose to lie there for a while, staring at the ceiling. Meanwhile, Tem rested inside my skull, exhausted. It took a lot of effort for a little slug-like creature to move a body this big for so long.

For all the incredible things Tem was capable of, his body had a lot of genetic imperfections and weaknesses. I felt sorry for him.

That's an arrogant thing to think, but I couldn't help it, and I couldn't hide my feelings from Tem. He understood that.

Anyway.

My life was busy. My family knew that I joined this new club called the Sharing. They believed I spent all my free time with them, having meetings and doing volunteer work. The best thing about that cover story is that sometimes it was actually true. The Sharing really did clean up the environment, support food banks, and wrote petitions to politicians. We really did have meetings to try and recruit more part-time members for the volunteer work.

But most of the time, when my parents thought I was at a Sharing meeting, I was in the Yeerk ship trying to save the world another way. With Tem's knowledge and my fingers, I did maintenance on the ship and upgraded the computer. Or I rebuilt broken technology we salvaged from crashed ships. Our group sent and received messages from aliens passing through the solar system. If they were hostile, we managed to drive them away. If they were peaceful, we made negotiations and trades, and respectfully asked them not to reveal themselves to the primitive humans.

I loved it, but it was hectic. Alien stuff ate up a lot of my time. After a few weeks, I came to a decision. I made one more change to my life.

"You're quitting the team?" my basketball coach asked in confusion. "Why?!"

I gave him some typical excuses. I had another extra-curricular. I wanted to focus on my grades. Stuff like that. But the truth was, my heart just wasn't in it anymore. The basketball team lost its appeal for me.

I didn't want to upset anyone by leaving. But frankly, I didn't care much what they thought either. My teammates just laughed it off back when I was insecure about my grades, like I was just being uptight. When I proudly told them about the afternoon I spent working at the food bank, they laughed again, like I had become weird for caring about that stuff.

The coach tried to convince me to stay. "But you're one of our best players. The team would be lost without you."

[If they're not a good team without you, they're not worth your time, are they?] Tem quipped.

It was so tempting to say that out loud. But instead I smiled and said, "The team will survive without me."

I didn't tell my parents I quit. And I definitely didn't tell Jake. I knew they would make a big deal out of it, and it just wasn't. I mean, it was just a game. Who cares?

I did tell the Sharing members though. I mentioned it to Tidwell while we were refitting the z-space transmitter and improving its interface with the language translation matrix.

"You quit the team?" While holding a small device, he gave me a suspicious look. "You're not trying to punish yourself for having an unfair advantage with schoolwork, are you?"

"For the millionth time, it's not cheating!" I was lying on my back, working with wires under the console.

"Whatever you say." I was pretty sure Tidwell and Illim were just teasing me about it at this point. Pretty sure. "Seriously, though. You didn't need to do that. We wouldn't mind if you spent less time here instead."

"I'd rather be here," I replied. "If it's between basketball and alien stuff, I'd choose here every time."

"What I mean is, you shouldn't have to choose just one," Tidwell said, as he used tweezers to insert redundant transponders into the device. "You shouldn't have to give up the things you love."

"I don't love it." I took the device from him and put it back inside the console. "I mean, the team. I still like basketball. I'm gonna keep practicing on my own. But the team has this whole 'winning is everything' mentality. And it's hard to take that seriously after fighting for your life against Taxxons."

Tidwell considered this. He nodded. "I see what you mean. Nothing like a hungry Taxxon to give you perspective."

I finished my work under the console and fit the cover back into place. "Before I met the Sharing, I was starting to worry that the only good thing about me was being 'the basketball champ'. But now I know there's more to me than that. Even without Temrash, there'd still be more to me."

[Not that I'm going anywhere,] Tem said to me.

"Not that he's going anywhere," I repeated out loud.

"No regrets, then?" Tidwell asked.

"No regrets!" I cheerfully confirmed. I got out from under the console and stood up straight. The computer screen came to life. It showed a star chart with tons of blinking lights throughout the galaxy.

Tem and I grinned. "Life is short, and the universe is big."


Author's Notes: Updates will be slower after this, but the story is not over.

I'm aware that in the canon, Tidwell is a teacher at the same junior high as Chapman. But I moved him to high school so that Tom and his age group would have more connections to the Sharing.