Mac stood on the deck looking out at the lake and was surprised that he was so sentimental about it. His family had spent at least a week every summer there when he was growing up but it had been five years since he'd seen it, or them. Rubbing the stubble on his chin he felt like he was the same person as then... three tours in Afghanistan and he still felt like the pimply teenager.
He'd been looking forward to this week for the last year. While he definitely wanted to see his parents again, he had to admit that he missed his sister Kim the most. Irish Twins as they called them, they were born only ten months apart. They'd been close as kids but then there had been something that got between them as teenagers. For some reason they struggled through their teenage years alone instead of as a team.
Kim had a weight problem. She never seemed to eat that much but she just couldn't get the weight off. Fat triggers cruelty in kids. Her high school was not fun. Mac had had his own issues. He was the worst athlete on any team he joined and he never made it into any of the other cliques in high school. Without an anchor like that, he'd drifted into hanging with the other directionless kids, smoking pot, and getting into juvenile crime.
The Army had straightened him out in more ways than he could count. Joining up had gotten the last criminal charges dropped and he'd thrived in the structure of the military. He found things he was good at and felt part of something. He also got into the best shape of his life, finding a way to be more comfortable and agile in his body. Luckily, these lessons hadn't cost him his life.
As he stood on the deck, the sun was setting giving him a beautiful show across the heavens. Soon sunlight was glinting off the surface of the lake, making him squint. After a few moments, he realized someone was coming out of the lake. In the glare he couldn't see who, but someone had been swimming, was walking out of the water, and headed straight for the house.
Kim was less than fifty feet away before the glare finally relented and let him recognize her. Except that he almost didn't. Instead of his chubby sister with the short hair, the woman walking toward him looked like a Bond girl. Kim's large breasts were still pretty large but her body was transformed, toned and curvy enough to give her an hourglass figure. Mac blushed deeply as he felt his cock stir in his shorts.
"Mac!" whooped his sister as she ran the last distance and gave him a big, wet hug. He returned the hug and a kiss on the cheek. She was wearing a string bikini and his hands held her bare back. He physically shook his head, trying to stop looking at her as a hottie and remember she was his sister.
"You're a little wet, Simba," he mentioned politely, using her childhood nickname. She laughed and stepped back, hands on her hips. His ARMY t-shirt was pretty soaked now. But he couldn't stop staring. She was so confident, so comfortable and graceful in her movements. So transformed from what she was before. He stared as she walked over to grab the towel she'd left for herself and began to slowly pat herself dry. His eyes noticed the curve of her ass, the way her breasts strained the bikini top, her long hair. Inside he groaned and told his gutter mind to stop fantasizing. You just didn't do that.
"When did you get in? How long have you been back in the US? Was it hard to go over there? Do you have a girlfriend? What are you going to do now?" The questions came in the usual barrage of Kim-thoughts and he laughed. Yep, that was his sister.
He started answering her questions as they stood there. Then he realized that she was checking him out.
"You shaped up pretty fine, Bear!" she whistled. "Gotta six pack under there?"
He blushed but pulled up his t-shirt to show her his tight, muscular stomach. She kept asking questions as she patted herself dry. He found it very distracting.
She led him inside while he tried to think of something to make his erection stop growing. He thought back to memories of the cabin. He and his sister had shared a bedroom in the upper loft as kids but eventually their father had built a wall between them to give them privacy once they got close to puberty. Luckily, he wasn't a great carpenter and there were plenty of little gaps and holes to let them whisper and giggle together.
Watching Kim's bottom wiggle into the kitchen made Mac remember spying on her through those holes, watching her dress, watching her practice kissing on her hand, and even watching her masturbate although that was really more listening since it had been so dark. Memories of jacking off to watching her bubbled up out of wherever he'd locked them away for five years. Keeping his erection down was becoming impossible.
He could swear that she checked out his bulge before handing him a beer. It was a quick glance. Did he imagine it?
Sitting at the kitchen table, they started talking and for awhile, he could forget that his sister was gorgeous now and nearly naked in front of him. He told her what he could do with his Army experience, focusing mostly on the state-side stuff. She told him about college and working on her master's degree in criminal psychology.
"The body?" she grinned. "Courtesy of Doctor Elliott. He uncovered a hormone imbalance. With the twice-a-day pills he gave me, I was in control of my body for the first time. This," she indicated gesturing at herself as she stood and posed, "Didn't come from a pill, but it took off the hand-cuffs I'd had all through high school. Now I eat right, at most one beer a day, and I exercise like crazy. Swimming team and volleyball team in college taught me ways to work out and have fun."
"I'm so proud of you, Simba," he said, his heart swelling with genuine affection for his sister. She smiled at him and came in for another hug.
"I'm proud of you, Bear," she whispered as the hug lingered on. "And I'm so glad your home safe to stay."
Kim kept mentioning that she should put some more clothes on, but somehow it never happened. They raided the kitchen for sandwiches and fruit.
"When are Mom and Dad getting here?" he asked before crunching a big bite of apple.
"Yeah, well, they aren't," said Kim. "Mom got pulled into presenting at a conference in Seattle and Dad decided to go with her."
"What about Simon?" After being overwhelmed by Kim's new look and catching up, Mac had almost forgotten about their little brother. Simon was a Junior in college now.
"He said he can't make it. I think he found himself a girlfriend at college."
"Huh. Not much of a family reunion," Mac mused, disappointed. He'd sort of built up the week in his mind as a way to get through the rough spots of his last tour.
"Well, I'm here," said Kim touching his chin to get his attention. "And we've got the place to ourselves until Sunday."
A shiver ran through Mac's body as he realized how sexually charged the room had just become. Kim was smoking hot now and he couldn't stop thinking about masturbating while spying on her years before. He knew how wrong lusting after his sister was. He felt it deep down. But he also had to admit that it just made it that much more hot that she was turning him on so much.
Kim pulled away a few moments after it had become awkward.
"So are you going to come with me?"
Mac gulped.
"The lake, silly. Lord, where your mind goes! Didn't they have women in the Army?" She winked at him and walked back out to the deck. He watched every swing and twitch of her ass in the tight bikini bottoms.
Within a few minutes he was down to his boxers and diving into the lake. He knew the drop off wasn't gradual, but still his hands, grabbed mud before he pushed up to the surface. His body was just different since the last time he'd done that.
Sputtering a little, he came to the surface and looked around. Kim was away from him a little way.
"Beat you to the raft!"
Sure, she had been on her college swim team, but there was no way Mac was going to let his sister beat him. He dug into the water and did his best to remember some kind of efficient form.
His hand touched the grimy wood of the raft and he pulled up to see Kim already on the raft, laid back like she was going to get a sun tan. The sun was gone and the lingering dusk was quickly deepening. Still, her white bikini almost glowed in the dark, hugging and accentuating her curves. Again, his cock got hard but it was hidden in the water.
"Simba beats Bear like always," she said with a grin.
"Grrrr!" growled Mac playfully as he levered himself half on the raft and pushed his sister off into the water on the other side with a yelp of surprise.
It was just like old times, splashing around until she yanked off his boxers leaving him naked in the water.
"Hey! Gimme those back!" he complained as he saw her swimming swiftly back to the shore. He was still holding on to the raft when he saw her walk out of the water and throw his boxers on the back of one of the old Adirondack chairs about thirty feet from the water. She sat down and waited for him.
The water was cold but it wasn't enough to get his hard-on down. He had to wait five minutes, looking at anything but Kim before he felt he could get out of the water without a flagpole.
"Oh, you wuss!" called out Kim. She got up, gathered up his clothes and took them into the house. Before things got worse, he swam hard for the shore and got out as quick as he could.
The back door to the house was locked when he got there, one hand trying to shield his cock.
"You know the rules!" came Kim's voice from inside the house. "Wash off the lake first!"
Grumbling, he ran over to the outside shower and worked to get the lake water and mud off himself. Happily he found a towel there. It was a small towel so while he'd be covered, it left little to the imagination.
He heard the door unlock and hustled to get in the house.
"You have filled out," Kim commented from a few feet away. She had a robe on now, light cotton but it covered her to her mid-thighs. She had wine glasses in her hand and a bottle of red. "Bet you're strong enough to make us a fire."
With that, she sat on the couch and poured the wine. Mac grabbed his duffel and hustled up to the top floor room. It looked a lot smaller than he remembered but the divider wall was still there with its peepholes. He threw on boxers, t-shirt, and shorts. Barefoot, he came back down to the living room.
It was still strange to be here without the rest of the family. It felt like a little fantasy bubble, just his sister and him. He mused that each of them were probably the best-looking they'd be in their lives.
As Mac made the fire, Kim turned the TV on. There wasn't cable or satellite at the lake house so she was watching a movie.
"What's the movie?"
