We've always been close, my brother and I. We've been inseparable for as long as I can remember. Most of that was down to the situation we grew up in. Perhaps I should go back a bit.

I'm Amy, my brother is Jack. We grew up in a small house with just us two and mom. I've never met my father and my brother was too young to remember him. See, he always had his "issues" and it put a lot of strain on my parent's marriage. When mom got pregnant with Jack, things got worse. Just months after my brother was born, mom was pregnant with me. It wasn't long until dad left. He just walked out, taking almost all of the money and leaving mom with a six month old and an unborn baby. I don't know what his "issues" were. Maybe he had drug problems, maybe he was cheating on mom, maybe he had something wrong mentally. Mom doesn't like to talk about it but I'm completely fine with that. If he'd do something like that to us then I don't want to know about him.

It left mom in the difficult situation of having to raise two children almost the same age whilst also working. Mom had to get a new job (which she hated) that included fairly long hours. She'd get home at 6pm and be in bed by 8pm. The hours were long but the pay was just enough to get a small place for us to live. Because of how small this place was, Jack and I shared a bedroom.

As we grew up, we grew closer. Even though there was just a year between us, I looked up to him a lot and he was very protective of me. We had the occasional argument or fight but that happens to all siblings. 99% of the time, we were the best of friends. Sharing a room didn't even prove to be much of a problem. Even when we were older. I always felt safe knowing my big brother was just a few feet away. We were so close that if you didn't know us, you'd think we were a couple. We'd hold hands, give each other quick kisses and other silly stuff like that. It's just how we were and our friends accepted it. Although, we knew to hold back during school. People there can be cruel.

Then changes occurred to our bodies. I went from flat-chested to a 32A which wasn't huge but at least I had tits. We saw each other naked a lot as you'd expect. It literally happened every day. However, because of how often it happened, we never really got embarrassed and eventually we just stopped caring. Every morning we'd be just feet away from each other as we took off our clothes to get dressed.

Then there was the issue of masturbation. I'd just turned sixteen when I discovered how good I could make myself feel. I preferred using my clit rather than fingering myself. Although, sometimes I was in a mood where I just needed something in me. I don't know when Jack first started but I caught him doing it a lot and he caught me a lot. Neither of us freaked out over it. If I walked in on him jacking it i'd just apologize and leave the room. He did the same if he walked in on me rubbing my clit. We understood each other. We knew we were both pretty horny teenagers who'd sometimes need to relieve themselves. We never went as far as to do it in front of each other. Although we were more comfortable with each other than most siblings, we knew there was a line somewhere.

Little did we know that the line would soon be crossed.

Mom had a week off work coming up and told us we'd be going to visit her sister Kate's family and stay with them for a few days. Jack and I weren't exactly thrilled, we'd much rather stay home or hang out with our friends but we didn't really have a choice. So we arrived at my aunt's house which was average sized but seemed smaller now that it was holding two families. Then as we finished bringing our things in, Kate gave me the "bad news".

"So it seems we have a bit of a problem" She began. "Originally, the plan was for your mom to sleep on the couch, you to sleep next to the couch on the spare mattress and Jack to sleep in the spare room."

"So what's the problem?" I said, sounding concerned.

"We may have slightly over-estimated the....usability of the mattress." She stepped aside to reveal the mattress. Springs were poking out, there were stains that I don't even what to know about and the entire thing was covered in dust.

"So where the hell am I meant to sleep? The hard floor?" I said, obviously upset.

"We're so sorry. We really didn't know."

Mom stepped in. "Look, I know it's not ideal but I think the only real solution is for Amy to sleep in the spare room with Jack. It may be cramped but it's all we can do for now."

"You may be right but the spare room only has a single bed and isn't very big" said Kate.

"They share a room at home anyway and they get along great. Sharing a bed for a few days shouldn't be too much trouble." Mom knew Jack and I were close, she may have thought we were a little too close at times but she was just grateful we weren't constantly fighting. "You two will be fine sharing a bed, won't you?"

We both nodded. Even if we wanted to protest, we couldn't and neither of us really minded.

Later, I talked to Jack alone. "Look, i'm sorry that i'll be taking up your bed tonight but we really don't have a choice in this."

He chuckled. "Just make sure not to snore so loud tonight. It's like there's a chainsaw in the room."

I punched him lightly in the arm. "Coming from you! Sometimes you snore so loud that you wake yourself up."

"How would I even hear my own snoring over Little Miss Chainsaw?"

We continued our banter for a bit then we hugged and shared one of our quick kisses before rejoining the others. The rest of the day went fairly normally. Typical family stuff. We went out to dinner, watched a movie, blah blah blah. Soon it was late and mom and Kate began dropping hints to get us to go to bed.

"It's getting pretty late. We're out early tomorrow morning. Getting some sleep would be a good idea."

It wasn't too long until we got the idea and went upstairs and into the spare room. Soon,Jack and I were standing over the bed. Just as I would any other night, I got changed into my sleeping gear. I unbuttoned my shirt and removed it before pulling off my shorts. I then reached behind me and unhooked my bra so I was standing there in just a pair of white cotton panties. I then took a large t-shirt out of my case (one of Jack's old shirts) and put it on, the bottom of the shirt falling just past my ass. Whilst I did this, Jack had removed his shirt and jeans. His body was quite good for a 17 year old. He wasn't bulging with muscles but you could see some abs on him with v-lines that disappeared into his boxers.

Jack climbed into bed first and moved right up to the wall so I could get in. Kate wasn't lying, it was definitely cramped. We moved around a bit, trying to get comfortable until I ended up on my side, facing away from the wall. I was pretty comfy but Jack was yet to find a good position. One thing I should mention about Jack is that he prefers to sleep naked. He did it all the time at home and was probably planning to do it here but once he found out i'd be in the bed too, he must have realized he should probably wear boxers. I guessed that was his issue and I was right as he moved his hand to his boxers several times to adjust them, lightly brushing my ass each time.

Eventually, he ended up on his side, facing the same way as me. He then positioned his arms so he was now pretty much spooning me. "Do you mind?" He asked. "It's just more comfy like this."

"Yeah it's no problem." And it wasn't. I actually like the idea of falling asleep in my big brother's arms. I felt safe.

Soon enough, he drifted to sleep and I was halfway there. I positioned myself slightly differently and felt something hard poke me in the butt. I reached my hand back to investigate and made contact with the tent in Jack's boxers. He had a boner. I knew that guys get them randomly so it might be that causing it or maybe being so close to a girl naturally aroused him. I wasn't freaked out by the fact he had a boner. I was freaked out by the fact it was pressing into me. My moving around caused it to move from pointing outwards to pointing up towards his belly button. I eased back into him and found that instead of poking me, his erection was now positioned between my buttcheeks.

I can't really explain what happened next. I'd felt his erection like this a few times before. When i'd sit on his lap he'd sometimes get hard and I could feel it. I'd move around on it and maybe bounce a little bit but i'd never realize what I was doing. It was like, I knew what was happening but it never registered. I was too busy moving around on my brother's erection to realize that I was moving around on my brothers erection.

Now it was happening again but i'd never felt it so much. I pulled my shirt up to uncover my panties so I could feel it more. Just his boxers and my panties separated his dick from my ass, It felt so good. I pressed my ass right up to it and began to slowly move up and down his shaft, wanting to feel every inch between my asscheeks. I don't know why it turned me on so much but it did. I continued for a minute before I picked up the pace a little bit. When I did , Jack made a noise and I crashed back to reality. I don't know if I caused the noise but everything suddenly hit me. I was just grinding on my brother's dick. What if he woke up? What if he was awake the whole time? The thought scared me so I pulled away from him a bit and lowered my shirt. Eventually, his erection went down but I couldn't get it out of my head. I had to have it again.

I woke up the next morning to find that Jack had already woken up and gotten dressed. Immediately, my mind went back to last night and how his dick made me feel. I even felt a little disappointed that I missed getting the chance to feel his morning wood against me. Jack made no mention of what happened so I guess he was asleep through the whole thing. However, I noticed he was more moody than usual, not just with me, with everyone. He was constantly getting annoyed by the smallest things. Come to think of it, I was getting pretty frustrated myself. Then it hit me. Remember how I said we masturbated quite often? It was several times a week. Jack did it nearly every day but because we'd been busy packing and doing other stuff for two days before arriving at Kate's, neither of us had got a chance recently. There was always a queue for the bathroom in the morning so taking care of things in the shower wasn't an option and we couldn't exactly slide away to touch ourselves in the middle of family activities. Conversation with Jack was normal. We talked about how we slept and he made no mention of being grinded.

"You actually weren't too bad last night....for a chainsaw."

"Oh shut up, you're the one who likes to cuddle. My big brother the cuddler." I guess he didn't know.

After another day with Kate's family, it was soon time for bed again. All day i'd been thinking about his erection. I knew it was wrong but it made me feel good so I didn't care. I stripped out of my clothes again and into my sleeping t-shirt only this time, I took my panties off too. Jack saw this and looked at me. He didn't seem to have any issue with it but I felt the need to justify it.

"It was just so hot last night, it was a little difficult trying to sleep. The t-shirt covers me up anyway. I hope you don't mind."

Jack shrugged. "Yeah, it was pretty hot, wasn't it? That's fine, why would I mind?"

I wasn't really lying. It actually was really hot but the real reason was just so I could feel him against me better.

So we got into bed and began trying to sleep. I got myself into the same position as last night and began hoping that Jack would do the same thing. He kept tossing and turning, clearly uncomfortable due to being restricted by his boxers so after a few minutes of this, I decided to take a chance.

"You can take them off...if you want."

"Huh?"

"Your boxers. You can take them off. I know you don't normally wear them to sleep, so if you're uncomfortable you can take them off."

"Um...are you sure about that?"

"It's fine, I don't mind." I didn't mind. I wanted it.

"Thanks."

He wasted no time as he quickly took off his boxers, leaving him completely naked and me with just a t-shirt. Jack seemed more comfortable and soon enough he ended up on his side, facing my back. I waited a few minutes before I started whispering to ensure he was asleep.

"Jack? Jack?"

No answer.

With that, I moved my butt into him and could feel his dick already semi hard through the fabric of my shirt, I felt it reach it's full potential as it moved my cheeks apart before nestling between them. I began to grind slowly against him as I had before. I don't know what came over me but I had to have more. I stopped and moved away to pull my t-shirt up before I moved back into him. There were no more restrictions. No clothes between us. It was skin against skin. No longer was this a little bit of grinding. I was fully giving my brother an assjob.

I was so turned on, it was too much. I reached down to my vagina and began to rub my clit. I couldn't stop myself from moving up and down his shaft faster as my fingers made a circular motion on my clitoris. I was so wet and out of control, all I wanted was to stay like that forever. Much like the previous night, Jack made a noise in his sleep. My grinding came to a halt as I listened intently but I noticed that he was still moving his hips into me. Maybe he was awake, maybe it was just a natural reaction in his sleep. I wasn't sure but in that moment all I cared about was my own orgasm. I grinded against him once more as my fingers resumed working my clit. I was getting close, I could feel it. Then I had the realization that Jack could be close. I started to move my ass away to prevent something bad from happening but I felt Jack's arms wrapped around me and pulling me back. I was too focused on cumming to fight it as my pace increased. I was seconds away from my climax when I felt several spurts of warm shoot up my back. He came.

"Oh shit, oh shit" I thought, panicking at what I just did. Surely, that woke him up. If my grinding didn't then his cumming definitely did. I laid there for what seemed like an eternity, waiting for something, anything to tell me if he was awake. All that happened was he pulled me closer to him to cuddle and after a few minutes, I got up to go into the bathroom. When I left the room, I swear I heard him whisper "Amy."

I got to the bathroom terrified of what I just did but at the same time, still turned on. I managed to wipe the cum off my back and shirt. I needed to finish myself. Knowing I could be fairly loud, I positioned myself on the toilet with one hand on the flush handle and the other between my legs. I picked up where I left off as I went to town on my clit, getting faster and faster as I panted, moving my hips to push myself into my hand. Enough was enough, I needed something in me. I put 2 fingers in my wet hole, keeping my thumb on my hood. Thoughts of my big brothers cock entered my mind. Thoughts of it between my cheeks, in my hole, his warm cum shooting all over me. I couldn't take it anymore and quickly flushed the toilet as I reached my climax, the flushing doing well covering up my moans as I had the best orgasm i'd ever had at that point. I remained sat on the toilet for a few minutes as I thought...