Derek's head popped up. "Did you hear that?"

"Hear what?" Emily's voice was slightly muffled by Derek's chest.

"That screaming. It sounded like Casey." Finally, Vicki comes through.

"Derek, do we really have to go check on her? Isn't Sam down there? Or Ralph? Or, you know, Truman? He's Casey's boyfriend, remember?"

"Yeah, they are, but I'm her stepbrother and you're her best friend, so we should probably go see what's happening. Besides, if Vicki's involved, Truman's probably involved." Derek paused and smirked. "Plus, there could be a girl fight." Oh, I HOPE there's a girl fight! Casey is fierce; she can totally take Vicki. And it will be SMOKIN'!

Emily smacked Derek on the arm. "Are you kidding me? You would rather leave here—now—to go see a potential girl fight between your sister and her cousin?"

"Stepsister. And yes." Emily's face fell. "No, no, no, not because I want to leave YOU here, now" --no, that really is part of it—"but because that was definitely Casey, and she sounded pretty mad." Besides, Derek thought, I can only do this for so much longer before I give in to her, and I really don't want to go there. That'll just complicate … everything.

Derek got up and checked himself—Hockey, hockey, hockey … Margaret Thatcher naked … OK, good—before dashing down the stairs to go rescue Casey from the inevitable scene between her and Vicki.

I hope Vicki stepped it up and made her move, Derek thought. She is such a slush, and Truman? Lizzie said it best: he's a cad. I hope this worked!

Derek followed Casey's increasingly shrill voice until he saw her in the back of the garden, screaming at Truman and Vicki and turning a delicate shade of lobster.

"And you, Truman, cheating on me AGAIN. At ANOTHER party. With my cousin. AGAIN. How could you?" Derek walked in on the last part of Casey's tirade and sidled up behind her.

"Hey, Casey, what's going on down here?"

"What's going on, Derek, is that I just caught my dear cousin Vicki kissing my boyfriend Truman. AGAIN." Casey was trembling with anger.

YES! Derek tried to hide his excitement. I probably need to look more appalled and upset about this … maybe protective … Derek rearranged his facial features to appear upset on Casey's behalf. That should do it.

Truman started, "Casey, I'm really sorry, she just kind of launched herself at me …"

"Oh, you liar, don't even try to deny it this time," Vicki interjected. "You came on to me. You kissed me. You suggested that we sneak off and have some real fun. I'm not complaining—Derek and Casey are acting weird anyway—but don't try to blame me for this."

"Vicki, are you kidding me? First Nick, now Truman? Twice? Will it ever stop? Can I ever date someone without you taking him away from me?" Tears threatened to spill out of Casey's eyes.

If she dated me, she would have to be scared of that. Been there, done that, never going back. Derek fought back the emotion bubbling under the surface. Even if he could let Casey know how he felt, here, like this, was not the way to do it. He was Derek Venturi, for crying out loud. Man's man, ladies' man, hockey stud. I'm not some mushball that professes his love in public venues.

"Hey, Case, I don't know why I'm really here, besides Derek inviting me, and I'm still trying to figure that one out. But since I AM here, I figured that I'd have some real fun, and it's not my fault that all the Thompson guys are losers." A wave of indignation rippled through the crowd. "So I'm here, and trying to make the most of this super-weird night. Oh, and don't blame me for any of this. Truman—your boyfriend, remember?--came on to me."

At that, Casey launched herself at Vicki with such force that it knocked both of them into the pond and under the water. When they emerged, spluttering, Casey had a fistful of Vicki's hair and a mouthful of words dirtier than Derek's hockey equipment. The crowd started to chant, "Fight, fight, fight!" and Truman just looked on, slightly shocked that he had indirectly caused this scene.

"Derek, you have to help me stop this!" Sam was at his side.

"Yeah, Derek, you have to help Sam stop this! That's Casey in there!" Emily was clinging to his other side.

I know that's Casey in there! She needs to stay! Go Casey!

"Dude, are you serious? You have a girl fight in your pond with two really hot girls! This is the best graduation party ever!" Derek didn't take his eyes off Casey, gleaming in the moonlight, exuding a ferocity that he didn't think was possible. If it wasn't for the fact that she's fighting Vicki for Truman, this would be better than those old videos of Dad's that I found. Derek laughed silently. It's still pretty awesome.

Sam spoke. "Um, dude? One of those 'hot girls' is your sister, and it looks like she's about to get punched."

Sam was right—Vicki was winding up to sucker punch Casey in the mouth.

"No!" Derek tackled Casey and knocked her out of the way, sending Vicki facedown into the water. The crowd murmured variations of "Did Derek Venturi just break up a girl fight?" Derek was on top of Casey in the water, and she was looking up at him with … what? Admiration? Gratitude? Longing? Nope, that's still just anger. She's pretty pissed at Vicki right now. The sight of her with her hair damp and mussed, her dress sopping and clinging to every part of her aroused in Derek intense protection and desire, and suddenly, he had to get off of her.

Derek leapt off of Casey, who was still flinging profanities at Vicki. Vicki, hair hanging in her face, returned most of Casey's insults with some form of "you're a goody-two-shoes who could never satisfy a boyfriend." The girls were still kicking and flailing their arms, but Truman had regained his senses enough to hold Vicki back, and Derek, Casey.

Sam appeared with towels for Casey, Derek, and Vicki. "Here, Casey, let me give you a hand." He wrapped one of them around her and handed one to Derek. "Here you go, D." The third, Sam just left on the pavement.

"Thanks, man. Come on, Case, let's get out of here." Derek relaxed his hold on Casey's arms, took her by the hand and led her out of the pond. Truman made a feeble attempt to catch Casey by the elbow, but she shook him off and walked away. A few steps later, she seemed to change her mind.

Casey stopped, turned around, and said loudly, confidence ringing in her voice. "Truman, in case you haven't figured it out, we're OVER."

Mission accomplished, thought Derek.