And maybe because someone was taking him seriously, Charlie chose to lighten up.

“OK, fine,” Charlie said. “You can call me Charles.”

“You can call him Charlie,” Rachel interjected.

We all headed to baggage claim. And as much of a spoilsport as Charlie wanted to be, I couldn’t help but notice that he talked Ryan’s ear off the entire way home.

NINE AND HALF YEARS AGO

Spring break of our senior year, Ryan and I both decided to stay in Los Angeles. But at the last minute, my mom found a deal on flights to Cabo San Lucas and decided to splurge. That’s how the five of us—my mom, Rachel, Charlie, Ryan, and I—found ourselves on a flight to Mexico.

Oddly enough, Charlie was perhaps the most excited about this idea. As we took our seats on the plane—Mom, Ryan, and I on one side of the aisle, Rachel, Charlie, and a strange bald man on the other—Charlie kept reminding my mom that the drinking age was eighteen.

“That’s nice, sweetheart,” she said to him. “That doesn’t change the fact that you’re still sixteen.”

“But it would less illegal,” he said, as he clipped in his seat belt and the flight attendants walked up and down the aisles. “It’s less illegal for me to get drunk in Mexico than here.”

“I’m not sure there are degrees of illegal,” Rachel said, scrunching herself tightly in the middle seat so as not to touch the bald man. He had already fallen asleep.

“Although I think prostitution is legal in Mexico,” I said. “Right? Is it?”

“Well, not for minors,” Ryan said. “Sorry, Charlie.”

Charlie shrugged. “I don’t look sixteen.”

“Is weed legal in Mexico?” Rachel asked.

“Excuse me!” my mom said, exasperated. “This is a family vacation. I didn’t bring you all to Mexico to get high and hire hookers.”

And of course, all of us laughed at her. Because we had all been joking. At least, I thought we had all been joking.

“You’re too gullible, Mom!” Rachel said.

“We were kidding,” I added.

“Speak for yourself! ” Charlie said. “I was serious. They might actually serve me alcohol at this place.”

Ryan laughed.

It really struck me then just how different Charlie was from Rachel and me. It wasn’t just in the superficial stuff, either, like the difference between brothers and sisters, high-schoolers versus college students. He was markedly different from the two of us.

Rachel and I were a little more than a year apart. We experienced things together, through a similar lens. When our dad left, I was almost four and a half years old, and Rachel had just turned three. Mom was still pregnant with Charlie. Rachel and I may not really remember our dad, but we had time with him. We knew his voice. Charlie entered this world with only my mother to hold him.

I sometimes wondered if Rachel and I were so close, if we meant so much to each other, that it prevented us from really letting Charlie in. By the time he was born, we had our own language, our own world. But the truth was, Charlie simply wasn’t that interested in us. As a little kid, he did his own thing, played his own games. He didn’t want to do the kind of stuff Rachel and I were doing. He didn’t want to talk about what Rachel and I talked about. He was always forging his own path, rejecting the one we had laid out for him.

But as much as we had our differences, it was staggering how the three of us had grown up to look exactly alike. Charlie may not have been similar to Rachel and me in temperament or personality, but he couldn’t distance himself from us genetically.

We all shared the same high cheekbones. All three of us got our dark hair and blue eyes from our mother. Charlie was taller and lankier, Rachel was petite and daintier, and I was broader, curvier. But we belonged together, that much was clear.

The plane took flight, and we started talking about other things. When the seat-belt sign went off, my mom got up and went to the bathroom. That’s when I saw Ryan lean over the aisle to whisper something to Charlie. Charlie smiled and nodded.

“What did you just say to him?” I asked. Ryan smiled wide and refused to tell me. “You’re not going to tell me?”

“It’s between Charlie and me,” Ryan said.

“Yeah,” Charlie piped in. “It’s between us.”

“You can’t buy him alcohol at this place,” I said. “Is that what you were talking about? Because you can’t.” I sounded like a narc.

“Who said anything about anyone buying anyone alcohol?” Ryan said, perhaps a bit too innocently.

“Well, then, why can’t I know what you’re talking about?”

“Some things don’t involve you, Lauren,” Charlie said, teasing me.

My jaw dropped. Mom was on her way toward us, back from the bathroom.

“You are!” I said, somehow yelling and whispering. “You are going to get my sixteen-year-old brother drunk!”

Rachel, finally having enough of all this, said, “Oh, Lauren, cut it out. Ryan leaned over and said, ‘Let’s see if I can get your sister to freak out over nothing.’”

I looked at him for confirmation, and he started laughing. So did Charlie.

“I swear,” Rachel said. “You’re as gullible as Mom.”

A LITTLE MORE THAN NINE YEARS AGO

I graduated magna cum laude. I missed summa cum laude by a fraction, but Ryan kept telling me not to worry myself over it. “I’m just graduating,” he said. “Not a single Latin word after it, and I’m going to be fine. So you’re going to be better than fine.”

I couldn’t argue about my prospects. I already had a job. I had accepted a position in the alumni department of UCLA. I wasn’t sure what I wanted to do with my psychology degree, but I figured it would come to me in due time. The alumni department seemed like an easy, reliable place to start out.

On graduation day, Ryan and I were at opposite ends of the auditorium, so we only spoke in the morning and then made faces at each other during the ceremony. I spotted my mom in the audience with her huge camera, Rachel and Charlie next to her. Rachel was waving at me, giving me a thumbs-up. A few rows back, I saw Ryan’s parents and his sister.

As I sat there, waiting for the moment when they called my name, it occurred to me that this was the end of so many things, and more to the point, it was the beginning of my adult life.

Ryan and I had rented a studio apartment in Hollywood. We were moving in the next week, on the first of the month. It was an ugly little thing, cramped and dark. But it would be ours.

The night before, Ryan and I had fought about what furniture to buy. He thought all we needed was a mattress on the floor. I figured that since we were adults, we should have a bed frame. Ryan thought all we needed were a few cardboard boxes for our clothes; I was insistent that we have dressers. It got heated. I said he was being cheap, that he didn’t understand how to be an adult. He said I was acting like a spoiled brat, expecting money to grow on trees. It got bad enough that I started crying; he got upset enough that his face turned red.

And then, before we knew it, we were at the part where we both admitted we were wrong and begged each other’s forgiveness with a passion unlike anything since the last time we’d fought. That was always the way it was with us. The I love yous and I’m sorrys, the I’ll never do that agains and the I don’t know what I’d do without yous always eclipsed the thing we were fighting about in the first place.

We woke up that morning with smiles on our faces, holding each other tight. We ate breakfast together. We got dressed together. We helped each other put on our caps and gowns.

Our life was starting. We were growing up.

I stood up with my row and followed the path up to the podium.

“Lauren Spencer.”

I walked up, shook the chancellor’s hand, and took my diploma. Out of the corner of my eye, I saw Ryan. He was holding a sign so small only I could see it. “I Love You,” it said. And at that moment, I just knew adulthood was going to be great.

SEVEN AND A HALF YEARS AGO

For the fourth anniversary of when we met, Ryan and I went camping in Yosemite.

We had been out of school for a year and a half. I was making a decent salary in the alumni department. Ryan was doing OK himself. We were just starting to get ahead of our bills a bit, starting to save, when we decided that a trip to Yosemite wouldn’t put us back too much. We had borrowed camping equipment from my mom and packed food from home.