When I was little, my dad was my best friend. We did everything together, and he was everything to me. I mean, I had many other people who loved me, like Chessy, but the relationship I had with my dad was special.

Then I met my twin sister at summer camp. At first we hated each other, which I guess is a weird way to react. The thing was, we looked the same, and we had similar talents and hobbies and stuff. At first it was scary, like a horror movie. Then it felt like she was trying to steal what made me me while also being all neat and proper with a cool accent. Hallie 2.0, better than the first model. Later she told me that she felt like I was Annie 2.0: braver, funnier, and more outgoing than she was.

Of course, then we spent some time together and began to sort of like each other. And then we found out we were twins, and that changed everything. We were so happy to be reunited as sisters. Then I had the idea to switch lives, and besides spending all our time together, we had a mission to complete. All of the time I spent learning how to be Annie and teaching Annie how to be me helped us smooth out most of the wrinkles in our relationship. We learned that we work better when we're working with each other instead of against each other.

Then I met Mom, and she was so amazing! Seriously, she was sweet and funny and intelligent and cool and – okay, I'm getting off-topic. The point is that meeting Mom was even better than I'd always dreamed it would be.

Annie's reunion with Dad didn't go quite as well, although I didn't fully understand that until later. There was Meredith and Dad always either with Meredith or talking about Meredith instead of spending quality time with Annie. Annie's time pretending to be me was mostly just stressful.

Then we reunited our family and everything went to hell. Well, it kind of went okay. Mom and Dad obviously still had feelings for each other, but they were still determined to keep our family separated.

So we resorted to desperate measures and hid both of our identities completely. We weren't sure it would work. We'd both made a lot of mistakes when we'd switched places, and it seemed impossible that neither of our parents would be able to recognize us now. Getting to know Mom was great, but Dad was my dad. He'd know me. But he didn't. He looked both of us in the face, pointed at Annie, and declared her me.

I spent a lot of time thinking that the problems started later, after Mom and Dad remarried, but I think some of them started right there. Something about the way I viewed both of them broke as I stood there in that hotel next to Annie. We didn't let our love for them or their authority over us sway us from our decision. We forced them to go along with what we wanted. And as heady as that was, it also meant that Dad wasn't my best friend anymore, and Mom wasn't the magical answer that had been missing from my life. It was now Annie who was my best friend and partner in crime. It was just me and Annie against the world.

I won't bore you with the details of the fateful camping trip with Meredith. You all know that Annie and I did our jobs brilliantly and succeeded in removing her from the equation. The only thing you need to remember from that happened right after Meredith gave Dad her ultimatum. She said her or us, and without hesitating he chose us. I was just happy to see him put the bitch in her place, but Annie gasped. It was almost like she was surprised that he'd so easily pick us over this random woman. I feel so stupid for not seeing it then, but there were bigger things on my mind.

And then, after all that, after Mom and Dad finally seemed to be reconnecting on their own, they still insisted on splitting up the family. It was horrible, of course, knowing that all our work had been for nothing, and it was heartbreaking saying goodbye to Mom. But it was devastating putting Annie in that car. I've always been independent, but I didn't want to go back to being just me without her at my back. Too bad it was only then that I realized the family I'd been fighting for hadn't just been about my parents. It had been to keep Annie. And we'd failed.

Luckily, that didn't last too long. Dad came to his senses, we flew out to England, and we got our happily ever after. I've never been happier in my life.

And for a while, everything was perfect. I had my mom and my dad and my sister. And, of course, Martin and Chessy and Grandpa. We all moved back to California (except Grandpa). Neither Annie nor I had to hide who we were anymore. We were all together, and our lives were full of fun and laughter and love. I mean, there were obviously complications with what to do with Mom's business and Annie's education and everything, but for the most part – yeah, everything was perfect.

I made a mistake, you see. I got comfortable. And when you get comfortable with people, you stop being afraid of fighting with them every now and then.

It was the angriest I'd been with Annie since those early days at Camp Walden. It started off small, with us bickering over who wanted to wear which shirt (our wardrobes had meshed a bit since the family came back together), Annie wanting to leave the light on to read while I just wanted to sleep, who got the last Oreo, who got to sit next to Mom or go horseback riding with Dad. Before we knew it, we were yelling at each other about how the one "always" wronged the other, and we were pranking each other like mad. It was a nasty few days.

Finally, Mom and Dad had enough and sat us down to make us work it out, but we weren't too keen on listening to them either.

After a lot of back and forth, Dad said it. "Sometimes I think it would be easier if the two of you lived in different countries again!"

Now, Dad isn't a bad dad. He's great, actually. He immediately looked horrified by what he'd said, even before Mom gasped, "Nick!" And I get it. People say things they don't mean when they're angry. I'd been doing the same thing at Annie.

But that didn't stop the pit of my stomach from dropping out at his words. Because if Mom and Dad decided to separate the family again, there wasn't much I could do about it. Just like I couldn't do anything that rainy day several months ago when they packed Annie and Mom off to England again. It was still possible for me to lose this family I'd fought so hard for.

Everyone had dropped into a horrified silence for too long by now. Dad took a deep breath and said, "I'm sorry. That was out of line. We are not separating this family again. But we do need to work this out. Your fight has gone too far."

"You're right," Annie said, softly. She turned to me. "I'm sorry, Hal."

"Me too!" I choked out, and then we were hugging each other and crying.

We still ended up grounded for a week, but the war was over. That night, when we were being tucked in, Dad leaned over me and softly said, "You know I didn't mean it, right? I wouldn't split you two up again."

I didn't know that. He could do whatever he wanted, like he'd done before. But I nodded and said, "I know, Dad," because I couldn't even think of how to respond any other way. What could I say? No, I don't trust you?

When Mom and Dad closed the door, Annie hopped out of her bed and climbed in with me. At first, we didn't say anything.

Finally, Annie whispered, "Do you think they'd ever do it? Split the family again?"

I whispered back, "I don't know. Maybe. They're happy now, but they divorced once. They could decide they were right the first time and divorce again."

"Or they could send me to live with Grandfather in England if they think I'm too much trouble," Annie replied. I hadn't even thought about that.

"I just..." I struggled to put my feelings into words. "I love our family, and I don't want to lose any of it. But you're my best friend, even though you drive me crazy sometimes. I don't want to lose YOU, Annie."

Annie made a soft sound beside me, and then we were hugging. I squeezed my eyes shut. I thought I didn't have to be afraid of losing her anymore. This really sucked.

"Ok, new rule," I said as we separated. "If we fight, Mom and Dad cannot know about it. No matter what."

"Agreed," Annie replied.

We both fell asleep in my bed and stuck close together the next day. Mom and Dad seemed a bit chilly toward each other, but they made an effort to do things together. We played a board game and then watched a movie together. It was like nothing had changed.

But the next morning, I woke up to see Annie putting on one of my favorite jackets. She turned to me with a smile that was a little too bright and said in a cheery American accent, "Morning, Annie!"

I just looked at her for a moment. We hadn't pretended to be each other since our parents got back together. We hadn't even hidden which of us was which since the camping trip. But Annie was looking at me pleadingly now, and I sort of got it.

"Morning, Hallie," I replied in a British accent. I immediately felt safer than I had since Dad's misplaced statement.

We didn't do anything unusual that day. We had breakfast and went to school. Annie chatted animatedly with our friends in an American accent, and I went to Annie's remedial history class and didn't slouch once. After school, Annie played a game of fetch with Sammy, who had long since gotten over whatever grudge he had against her. When Mom mentioned something in French that evening, I had picked up enough of the language to give a short reply. We did our homework, played a game of poker, and then were tucked into each other's beds.

And no one noticed a thing. No one so much as suspected that I was Hallie and not Annie.

After the door was closed, I crawled out of Annie's bed and returned to mine. Annie didn't leave.

It was our safety net, see. We were both clever or devious or whatever, but the only thing that had ever worked as leverage against our parents was that we were the only ones who truly knew which of us was Annie and which was Hallie.

It's not like everything was awful after that. We were still a happy family, and we did fun stuff together. But a few things changed.

First, Annie and I stopped outwardly squabbling. We still bickered or pranked each other in private when we got on each other's nerves, but to our parents and the rest of the world, we were nothing less than a united front.

The second thing that changed is that we started switching places again. Not all the time, and not always for a full day. Just sometimes I'd slip into Annie's accent and she'd slip into mine. And every time we did, I felt safer.

Third, it became more common for us to sleep in the same bed. It reminded me of the weeks in the Isolation Cabin when we pushed our beds together.

And fourth, I began to suspect that maybe, just maybe, Annie and I weren't ok.