My Sister's Bet

"Ready for our 45 minute run?"

"Forget it..." she managed to reply. "My head is still spinning!" she cried.

"Ooh. Did you drink water in the bathroom, just then?"

"Nope."

A minute later, I was back in her room with a huge glass of water for her. "You're dehydrated... You should know better, miss trainer."

"Pfff..." she said, reaching for the glass.

It was still very dark in her room, but I saw the silhouette of her right breast as she reached for the glass. I pushed my luck "Feel like getting a massage?"

"Oh gods yes! Would you?"

"Of course... You've given me one nearly each morning, all summer long."

"Oh, wait... I'm naked." she said, smiling a lazy smile. "Throw me my underwear."

Looking around, I found her magical green bra and panties, and couldn't help but steal a long look at the bra. "There you go." I said.

"Ha! You liked that bra from yesterday, didn't you?" she asked, grinning.

"Er, well..." I mumbled.

"Cut it out! I saw your eyes bulge last night! Crazy, no? Given that you've been staring at my breasts in a bikini everyday..."

"Well, not quite the same effect."

"I know... But it won't work for a massage. Take the blue one in the second drawer."

It wasn't a super sexy bra, but it wasn't a huge sports bra either. "There you go again."

"You have the oil?" she asked while putting her underwear under the blankets.

I spent the next half hour massaging, caressing, enjoying and revelling in my sister's tight body. Gradually she came back to her usual self and soon we were chatting. When she turned on her back and I did her front, she glanced at my hard cock through my boxers. "Even after two months? Thanks, bro!" she grinned.

"Thank you, Peach. Three months ago, could you have imagined that I would give you a full body massage in your bed, wearing nothing but flimsy underwear?"

"Nope, never. I'll have to thank Jen for that!" she laughed.

"Thank her for me as well! I got the better of this deal, sis! I think I'm going to miss these mornings and special staring permissions once Fall gets here."

She looked at me, from between her breasts, with a soft smile as I massaged her thighs. "Me to, big brother." After a brief pause, she said "Think you could do 35 sit ups this morning?"

"Aw... No way. I'm sorry if I'm not getting better fast enough. I'm going to die before getting to 35."

"Shit... All that hard work..." And then, just like what happened at the very beginning of this crazy bet, her face changed, and I knew she'd had an idea. "Hmmm, just how much do you like my green bra?"

"Er, quite a lot, why?"

"Give me thirty minutes, and meet me in the backyard, already warmed-up. Think you can jog alone today?"

"Maybe, yes, just today..." I replied, a half-smile on my face. Fixing her ass while I jogged had become a wonderful combo.

"Ok, see you then!"

When I ran into our backyard, a bit sweaty but not drenched like I was at first, I stopped dead in my tracks. Peach was standing in the yard, with her green lingerie. And while, in absolute fact, her red bikini exposed more skin, I was nonetheless shocked. Shocked at just how sexier she looked. Fuck! I felt a buzz in my lower belly and had to refrain from growling out loud. My body, flushed with hormones from the run, knew what it wanted. "Come here and do 35 sit-ups. Right here and now. I know you can do them." And so I came. So to speak, at least. I was used to those sexy sit-ups, bringing my face near to her bikini cleavage. And so I sped through the first twenty sit-ups as usual: Peach was squatting and holding my feet down. But this morning, I made it to 27 a lot easier, staring into that wonderful cleavage.

When I began to groan with each repetition, Peach repositioned herself. She moved in much closer, sitting herself on my feet and holding my thighs with her hands. And she leaned in. When I came up for my 28th, I was really, really close to her breasts. I had become used to being maybe ten inches away, but now it was three. Very fucking close. 29, 30, 31, all the same. I had never broken 30 before, and had four to go. As I went back down, I said "What if I can..." then paused as I got up, then added "touch them?" as I rose for my 32nd.

"I'm not gonna move until you reach 35."

I rose for my 33rd and reached as much forward as I could. Maybe one inch away. As I fell, tuckered out but convinced I could reach them, I took a quick deep breath and pulled up again. And so, for the first time, I kissed the inner swell of my sister's left breast. Down, then back up again, and I licked her right breast from the exposed base until it flared out on her chest. When I crashed down after that, Peach said "Keep going brother... If you can reach them again, I'll hold your head there for a few seconds." My eyes bulged wide opened and I tried again. I was experiencing more pain than ever before, but I knew I had to do it. And so I did. And Peach kept her promise. For those few very quick seconds, I had my face buried in her cleavage.

Peach didn't have very large breasts, but she was wearing a bra that made them seem much larger, was bent forward, arms in front to hold me, and, most of all, she was my sister. I had my face buried between her breasts, kissing and licking as much skin as I could find, even darting my tongue under that magnificent bra. Instead of letting me fall back down afterwards, she gently guided me, following me most of the way. She ended up nearly on all fours above me in her sexy lingerie, my hard cock obvious and my saliva all over her cleavage. "There you go..." she whispered as I trembled, for many different reasons. "I knew you had it in you, brother!" I was in so much pain, and my brain was still overwhelmed. I only managed a little smile.

A bit later, when I managed to get up, she had dried her cleavage with a towel and was walking back towards me, grinning. Still worried, I asked "Are you sure about this Peach?"

"About what?" she asked, apparently genuinely puzzled.

"Well, I mean... about... my face in..."

And then my sister, my sweet sister who had allowed me to kiss her breasts, began laughing. "You worry too much, bro. Are you enjoying this... whatever this is?"

"Of course!" I briefly looked at my shorts, where my erection was plainly visible.

"Do you believe you're forcing me into this?"

"Well, no, but—".

She interrupted me "Know one thing, brother. I'm not going to do anything I might truly regret for that bet. And the same goes for you." she said, leaning in close to my ear to whisper "The moment you don't want to kiss my breasts, just let me know and I'll stop you."

We laughed again and spent the rest of our two hours together having a lot of fun despite the pain. The lingerie helped. A lot in fact. It's strange how human motivation can work, sometimes. We made sure to be decent before anyone would come back home, and I spent the evening relaxing, preparing for tomorrow. In my bed, as I was getting ready to finally masturbate to images of my mouth on Peach's breasts, she opened the door. On all fours on my bed, she leaned in and whispered "Tomorrow morning, you're going to do the full hour jogging with me. I'll give you something to look at... Believe me you'll want to follow me."

And so I did. I did get my morning massage, with her red bikini again. But I did get the feeling that I was feeling more of her body. Usually she moved from top to bottom, but this morning, after having done my legs, she moved back up, sliding her own inner thighs around mine. When she worked on my back again, I could feel her skin gliding on mine. And while I was on my back, the feelings were even more intense. Once, when she reached down to get the bottle, one of her breasts grazed my belly. It had never happened before. An accident, perhaps? Before finishing, she leaned forward and used her entire forearms to massage my chest, forcing her breasts much closer to my skin.

After my shower, I met with her outside, and was really pleased to see that she was wearing a skirt. A very short skirt. "Ready to watch me run and bounce around with this?"

I grinned, shaking my head. "You little tease!"

"I'm only a tease if you don't get to see anything... What if I told you that I'm only wearing a g-string under it?"

I couldn't reply, and motioned her to run. We did our one hour. One full hour of jogging. It was mindbogglingly pleasant. When we ran through the part of the trail in the forest, I noticed that Peach began to jump and bounce around a lot more. So did her skirt. I could see most of her ass as she did, a lot more than her bikini revealed. There was a steep cliff near the end of the forested path, and usually it was hellishly difficult for me. But now, I was looking forward to it. Looking up her skirt as she ran all the way up, I was panting and grinning. Peach suddenly stopped, and said she had a small cramp in her thigh. She then proceeded to bend forward, stretching herself. And, obviously, showing me her ass completely. I stared at her, fascinated by the sight. She laughed as she resumed running, daring me to catch her.

That entire week was mesmerizing. Lingerie, skirts and g-strings fought with each other in my mind, and the breast-kissing sit-ups became the norm. Once, as she was holding me for the final gift, I felt my tongue reaching her nipple under her bra, feeling its taut, hard and excited flesh. I was briefly afraid that it would piss her off, but she simply smiled as she gently lay me down afterwards.

The next week was even more intense. Both more gruelling and wonderful. The early massages had once again become more than just fun: I truly needed them after what Peach put me through. But everything was becoming even sexier. It was otherworldly. At one point, she removed her g-string from under her skirt as we entered the forest for our jog. And then she sped up like the damned road-runner. But I caught up quick, amazed at the naked glances I was now allowed. When she reached the top of the cliff, she slowed down, allowing me even more. I saw her pussy flashing, confirming that she was mostly shaven.

When she paused at the edge of the forest, I expected her to put her g-string back on. Instead, she handed it to me and said "If you can get back home before me, I won't wear them for our entire jog tomorrow." And then she sprinted. But that was a miscalculation on her part. Speed had never been an issue for me. I was significantly taller than she was, and had always been a good sprinter. Long legs will give you that. And in the past few months she had given me a lot more endurance. We had about a ten minute run in front of us, at most. I passed by her after three minutes, and despite her best efforts, she couldn't catch up to me. And the next morning's jog was indeed panty-less. Which was amazing. After that morning jog, I had a very good idea of what her pussy looked like. Even more amazing, that panty-less run became the norm.

It was just crazy. Then, as the deadline drew nearer yet, Peach stepped up the craziness even more. Before we began our sit-ups, she said that if I hit 40, she'd remove her bra. And as magnificent as that bra was, I really wanted it off. By 32 I was kissing her breasts, not even slowing down. When I hit 39, groaning all the way, I didn't even bother trying to kiss her breasts, but forged on to 40. Peach was laughing as I crashed down after my 40th sit-up, and unclasped her bra. She placed her hands on her hips, grinning and red faced as I stared at her breasts. They were as stunning as I thought. They were not overly large, but they were still round and full, thrusting forward proudly. Laughing, she made them bounce left and right a few times as I stared at the pale pink aureolas and nipples. What Peach hadn't counted on was the fact that I had enough energy left for one last sit-up. She cried out as I sat up again and closed my lips around her left nipple. In reflex she placed her hands on my head, pulling me close. A few seconds later, she felt me shake and tremble and she guided me back down.

"Damn!" I said, pain threatening to overwhelm me, as much as pleasure.

"You sly devil!" Peach said, grinning and even redder. "Do you realize that you've now officially gone further than Matthew?

"What? Get out of here!" As crazy as things had been, it had not prepared me for the following conversation.

"I'm serious." She took a deep breath, but didn't reach for her bra. "In fact, we both want to go slow. I went too fast with Jordan, and I really don't want to make that mistake again."

"Oh..." I didn't know what to say or do. "I'm sorry?"

Peach turned to me and smiled. "Thank you, even if you're fumbling for the right words." with that, she lay down on the grass next to me, on her back, still braless. "Can you keep a secret?" she asked me.

"Peach, do you really need me to answer that? Do you realize that if any of what we're doing were to come out, we'd be in fucking deep trouble?"

I was really glad to hear her laugh out loud. "You're right. So, here goes: I'm not even sure I'm technically a virgin anymore."

I wasn't expecting that. It took me a while to react. "I, er, didn't think you were, actually..."

"Really?" she seemed genuinely surprised.

"You've had quite a few boyfriends already, and are, blindingly obviously, very at easy with your body. And in any case, how can you not be sure?"

"Remember Kevin?"

"The bastard? Yeah I remember."

"Well, we were fooling around, naked in his bed. I made him promise that we could do anything except penetration. And it was really, really fun. Until he tried to penetrate me. And he did, at least part of the way."

"Fucker... He doesn't know what's coming his way the next time—"

"Shhhh brother. Let it go. I've made my peace about that. But did he penetrate me deep enough?"

The entire conversation was utterly strange. Peach and I had gotten very, very close in the last few months, spending inordinate amounts of time together, working and talking. The strange physical intimacy, usually not shared between brother and sister, had definitely allowed our relationship to deepen. Judging by her actions with me and her confidence, I knew she was perfectly at ease with her body and with sexuality, despite her young age. She seemed a lot more confident than I was, in any case.

"Penetrate you deep enough? To count as losing your virginity?"

"Yeah..."

"Nah... No he didn't. I think you'd know, and in any case you're going to lose it when you decide to. Look, " I said, taking a pause. "I've had sex maybe five times with my current girlfriend, so I'm not an expert. But I'm pretty sure you get to decide."

"Bah, it's not that big of a deal... It's not as if we were still saving ourselves for years until our wedding night. I've found that I get bored when my friends talk about the big night. But you're right, I think I'm going to give it to whoever I want, regardless of what Kevin did."

"Good for you!" I said, turning on my side, and marvelling at the fact that she was still topless.

"I'm a virgin then!" she added laughing.

"Yeah... The most confident and sexually awake virgin I've ever seen!"

"Thanks big brother!" she said, before kissing me on the lips. Really quick, almost innocent. Then, without leaving me time to react, she got up and said "Now, we have to find a way to make you work on your push-ups. Hmmm, still wanna stare at my ass? Are you bored yet?"

I grinned, shaking my head. "Nope!"

"OK then, you're going to get your best look yet! Do 30!"

As I was labouring through the first 20 pushups, I wondered what she had in mind. As I called 25, she dropped on all four right in front of me, her panty-clad ass way up in the air. In that position,I could only look at it when I was fully up. But boy could I look! Soon I realized that she wasn't really offering me her ass. Instead, it was her pussy that was in obvious display. She had her own legs below me and between my arms, so when I pushed up I was just about touching her. At this distance, the lace of her panties became see-through, and I got quite the view. Soon I was going for 30, before crashing to the ground.

"See what happens when you're properly motivated?" she laughed.

The toplessness became part of our daily routine, but usually we stayed indoors for that. The pussy tease as well. Three days later, as I was pushing up for my 26th push-up, I called her a tease. Her answer was simple "Do 30 and I won't tease anymore." I felt a rush of pleasure in my belly, and renewed strength. When I did reach 30, her hand appeared and pushed the crotch of her panties aside. I had gotten very good looks at her pussy every time we ran up the forested path, but this was something else. I was shaking as if an earthquake had its epicentre in my chest, but I remained there as long as I could. Five seconds. But five glorious seconds. Sprawled on the grass, trying to control my pain, I croaked "Damn it Peach... You're fucking gorgeous from very damn angle!"

"Wow... Gracious even when exhausted! Wait and see what I have in store for our jog tomorrow... Fifty minutes."

"Only fifty?"

"Yep. The same route though, so we'll have to go quicker."

"Crap..."

As I went to bed that night, having seen my sweet sister naked from every angle, having sucked on her breasts more than once, I was rock hard. That too was now part of my routine. I masturbated while thinking about her, cumming inordinately fast without the need for porn. When I saw myself in the mirror behind my door, I was shocked. Mom and Dad had made some comments, but I thought they were just encouraging me. But after ten weeks or so, the results were clearly visible. I had lost a lot of flab and gained muscle mass, and I knew that my cardio was above and beyond what I had before. I cleaned myself as good as I could and went to bed. As I reached for my boxers, I paused, and decided to let them there. It was only fair that Peach would see me naked. I almost masturbated again before going to sleep, but resisted the urge.

When she opened the door the next morning, her red bikini telling me that we were alone, I turned on my stomach. When she pulled the sheet and gasped, I turned my head around and looked at her. She was grinning and said "About time!" and we were laughing together. I had never been so at ease and comfortable with another girl in bed. The fact that she was my sister made things a bit stranger, but somehow a lot naughtier. The back massage went pretty much as usual, but when I turned around, Peach kneeled above my thighs and stared at my cock. "Hmmm, very nice big brother. Very nice. Gisele is a lucky girl..."

"Well, that may be, but she doesn't seem to want to have sex all that often."

"Yes, you told me... four times only, and eight months together now?" she asked.

"Yeah."

The utter abnormality of the situation didn't even register, for either of us. We were brother and sister, talking about our sex life, while she was massaging me, wearing nothing but a tiny bikini, and I was naked, my erection proudly displayed. The only time I felt her hesitating was when she did my shoulders, forcing her to bend further forward, making her belly touch my cock. But even then, she fumbled with a single word and kept going. Before finishing, she sat up straight and looked at my erect cock. "I'm no expert, but that's a really nice cock... Shame on Gisele if she doesn't want to enjoy it more often..." she sighed. "Meet me downstairs in ten minutes!" As I showered quickly, her last comment struck me. That was rather intense, despite everything.

As we ran, her with the same skirt and no panties, I tried to discover what she had in mind. When we came to the forest, she stopped, and asked me if I was ready to run really fast. Of course I was. In seconds, Peach had stripped completely and said "If you can catch me, we'll do your exercises naked at home!" And she bolted. Like a young colt. After just a few steps, she threw her few clothes (camisole, skirt and bra) up in the air. "Bring my clothes!" she cried as she disappeared around the first bend. Shit! I was faster than she was in a straight line, but this was no straight line! I grabbed her clothes as fast as I could and exploded after her.