What about the twins get into an argument about who likes Hidari (but it's really their plan to get Kaoru and Hidari together) and they make Hidari choose one of them, but she chooses Hikaru instead 'cause she figured out their plan and now has a secret plan of her own? This chapter has been greatly helped by DotDotCurve:)

*Kaoru POV*
*Flashback*
"Hey Hikaru, what're we gonna do about Hidari?" I asked my brother in the car on our way to her house.
"Hrrm, I think we should have fun with it!" he said.
"How so?"
"Okay, she likes us, BOTH of us, right?"
"Yeah."
"Well, how about we make her choose one?"
"But, that's rude."
"Yeah, when'd you go soft? Do you have a crush on her?"
"WHA- N-no!"
"Then let's play our game!"
I resigned myself and Hikaru do whatever he wanted, dragging me along.

*End of flashback*
*Hidari POV*
The twin said they love me. WHAT?! I stared at them for the longest time, my brain FRIED.
"Do you love us?" they asked.
That did it, I snapped. Everything I thought about them came out in one big rush.
"Guys, when I met you, I thought you were the greatest people I'd ever met. And when I got lost, I kept hoping you'd find me. When you stayed the night at my house, I had the best night of my life. When Kaoru and I accidentally kissed, I thought I was in heaven, but I also wished he was Hikaru. When Hikaru asked me how I felt about Kaoru, I got nervous and my palms started sweating. I didn't know what to do. When Kaoru and I were locked in a room together, I wanted to kill Hikaru, but I also wanted to curl into a little ball and just sleep, next to Kaoru. And just now, when you said you loved me, my first thought was 'I love you two so much more'! What do I do?" I said, almost crying.
It was their turn to stare at me. Kaoru looked like he'd won the lottery, but Hikaru looked hurt. I hugged Hikaru and ACTUALLY cried. Hikaru instantly wrapped his arms around me and held me there while I cried. When I stopped, I'd noticed that the whole club was watching me. My face became beet red and I went to hide my it.
"YOU TWO KISSED?!" screamed Tamaki.
"YOU GUYS DIDN'T TELL THEM?!" I yelled, my face getting even redder.
"Well, did you WANT us to?" asked the twins.
"Of course not!"
"Well then you shouldn't be mad!"
"I DON'T KNOW WHAT I AM!"

*to the beach!*

I jumped out of the limoe as quickly as I could and then saw that the beach was empty. I looked around a bit and saw no one. Then Tamaki explained that this was a hosts only vacation so we could be refreshed and blah-blah-blah. He just wanted to see Haruhi in a bathing suit. I went into the girls bathroom and put on a plain black bikini and walked out.
"Hey, you actually look female!" yelled the twins.
I smiled. "Yeah, but I'm still Hidari."
"Okay!"
I pulled out a squirt-gun and shot them both in the face. They chased after me and we played water tag for a while. After that, we just walked along the shore, it was dusk and I couldn't WAIT for night. Hikaru was on my left and Kaoru was on my right. It was perfect, but then they brought IT up.
"Um, we really like you," started Kaoru "But you need to choose one of us!" said Hikaru.
"I, I, I've gotta think about it..." I muttered.
They nodded and we started heading back to the hotel. When we got there, I made a beeline for my room. I had to have time to think about this. The best place to do that would be somewhere I can be ALONE, but that isn't available! Hikaru is funny as hell, mischievous and absolutely adorable! But Kaoru is really smart, adorably awkward, and likes all the same music as me. After about an hour, I went with Kaoru.
I went downstairs to tell them my decision, but got stopped short by them on the steps. They were talking, about me.
"Hikaru, I think we should quit the game," said Kaoru.
"What? Afraid she'll choose to date you?" Hikaru shot back.
"NO! I don't care WHO she chooses!"
"Well then we're going to keep playing, seeing as she's BOUND to choose you!"
Then they kept walking. I wanted to cry. It was a GAME! They were toying with me! That pissed me off and then Kaoru says he doesn't care! That's IT! I'm done, Hikaru it is. Bound to choose Kaoru, SURE!
I walked down the stairs as calmly as I could and sat down in between the twins.
"Guys. We need to talk. NOW," said, trying to be urgent and nervous sounding.
"Sure!" they said, glancing at each other. As if I wouldn't notice!
We went into the hallway and I told them my 'decision'.
"I made my decision. Its Hikaru..."
"Oh great! Congrats Kaoru, you did it! WAIT! WHAT?!" Hikaru burst.
"I choose you, Hikaru."
"Umm..."
"Anything you want to TELL me?"
"No! Lets go!"
He grabbed my hand and marched us into the kitchen. Then Tamaki piped up.
"Are you two together?"
"Yeah, what of it?" Hikaru growled.
"Yeah, is that okay?" I said at the same time.
We looked at each other and started laughing.
"Uh, its fine, I think..."
After dinner, I went up to my room and started hitting the wall as hard as I could. Just when my knuckles started to bleed, the power flashed out due to stormy whether. Lovely.