Kelse

When I was younger, I was never very popular and if it wasn't for my asshole brother, Chad, I wouldn't have even met my best friend. Chad and Karin's relationship began before I met her, Chad being the allegedly cool older guy and Karin being young enough to still be impressed by a guy with a reliable car. As much as I didn't get along with my brother, I detested his most recent snob of a girlfriend so when he asked if I'd be willing to keep it a secret if he brought his side girl over to the house after school, I happily agreed to stick it to her.

What I didn't know was not only was she my age but she was even in my class at school. A routine came about where she'd walk over to our house after school to hook up with my brother and leave before our parents came home. I guess one day he forgot to tell her he wasn't going to be home, so it was up to me to answer the door and let her know. I answered the door to tell her Chad wasn't home, and that was how we met. She was pretty annoyed Chad didn't tell her, but asked if she could come in to use the bathroom, one thing led to another and we ended up bonding over making fun of my brother.

For the next couple months, every day she'd come home after school to see Chad but stay longer and hang out with me. We became such good friends the lines became blurred as to which one of us she was actually coming over to see, although Chad always got to have her first. Like clockwork, they'd usually take about twenty minutes and then we could hang out so I'd find myself watching the clock waiting for them to be done, which turned to listening. If I pressed my ear to the wall I could hear Karin's soft moaning.

Karin became two different people to me: my platonic best friend who I would hang out with every day and the erotic moaning in my wall I would masturbate to while waiting for my friend.

Soon everything would change in ways neither of us could imagine.

Karin

It was Friday and Chad and I were hanging out in his room like usual. Things were a little off with us since things with his girlfriend were apparently getting more serious. I never quite understood why he was with me if he could have her, she was older and had a full woman's body, I was just happy he still paid me any attention since I knew if he had to choose between us, there's no way I could compete with her. I knew I wasn't ugly, but her BMW and big D tits beat a stupid sixteen-year-old redhead with (not quite) B cups- and I honestly wouldn't even blame him. We had been together, if you can even call it that, for a few years and he was the only guy I'd been with so I wasn't really looking for anything else.

Plus I had gotten close with his family, especially his sister Kelse. Sometimes I wonder if I'd still be hooking up with Chad if I didn't get to hang out with her afterwards. She's pretty shy but once she opens up, she's a lot more mischievous and fun than people realize. In a way, I have the perfect relationship where I get to have sex with Chad and hang out with Kelse afterward, the two of them together providing a totally fulfilling relationship neither one of them could give me by themselves.

I didn't want things to get weird between Kelse and myself so I did my best to stay quiet when I was with Chad, but he makes it hard for me sometimes. His girlfriend texted him she was going to drop by so we had to be quick and keep an ear out for her car door in case she was early, I also agreed to keep most of my clothes on in case we had to bail in a hurry. I flipped my skirt up and pulled my panties to the side while he bent me over. He finished much faster than usual and after he pulled out I was already dressed so I straightened out my outfit and went next door as usual, although Kelse wasn't sitting on her bed where I usually greet her.

I poked my head in the door to see if she was in there but it took me a second to register what she was doing. Her back was to the wall and her hand was in her panties playing with herself. A flood of questions hit me all at once: Was she listening to us? How often does she listen? Should I let her know or pretend I didn't see her? Should I be flattered or creeped out?

But before I could make sense of it, she opened one of her eyes and snapped her hand out of her pants. Her face turned beet red and she was at as much of a loss for words as I was.

"I uh..." she stammered.

"No it's cool, I'll pretend I didn't see it if you do," I responded.

I told her it'd probably be best for me to take off before Chad's girlfriend came over and I think she was relieved.

When I got home, I found myself still thinking about walking in on Kelse. Maybe it was because Chad didn't provide his standard good work but I found myself with my hand in my panties thinking of Kelse. Surly she wasn't listening to hear her brother, so she was masturbating thinking about me? I never thought about what I sound like, is it hot? I barely know what I'm even doing, Chad tells me what to do and I do it until he finishes. He's the only guy who's fucked me but I'd guess he's bigger than normal and I usually finish, maybe it actually sounds pretty good to an eavesdropper. I'll definitely have to pay more attention next time.

But right now, my fingers were getting wet while I thought about watching Kelse. I wonder if I made her as wet as I am? I don't think I'm a lesbian, but she's not bad-looking as far as girls go. Nice face, big tits, easily bigger than Chad's stupid girlfriend. Thinking of Kelse's large breasts actually caused me to bite my lip and I grabbed the bedsheets with my free hand. I didn't even know what I'd do with them, but I wanted to see them all of a sudden more than anything in the world. I arched my back and let out a loud moan as I came.

My head was spinning all weekend thinking about what happened, should I tell Kelse? Would that make things more even between us, or would that just be weird? Either way, it didn't matter because she wasn't texting me like she usually did. I had to figure this out, I hate things being weird with Kelse but I also can't stop thinking about her playing with herself. I had an idea; it wasn't good, but it was all I could come up with.

Kelse

It had been all weekend and I hadn't talked to Karin. What could I say? "Sorry friend for secretly masturbating to you like some creepy stalker dyke" would probably be a good start. How would I feel if she were to masturbate thinking about me? It doesn't matter because she's obviously not like that, the entire reason I met her was because she was sleeping with a dude, my brother. She's not a lesbian, and I'm not convinced I am either, but good luck convincing her that. Things are going to be weird now and I fucked it up being a perve. Honestly, the weirdest part is I don't think I'm even a lesbian, it just turned me on hearing them having sex, but I should at least apologize before she comes over today.

I was in the middle of trying to untie the Gordian knot when I saw she texted me:

"Hey Kels, sorry I walked in on you yesterday. I want things to go back to exactly how they were before it happened."

Karin

Chad seemed as distracted as usual, but today I'd get his full attention. I knew Kelse would be in the next room as always, but she'd be too embarrassed to be listening so I'd have to be loud enough for her to hear me from her bed. Chad was texting on his phone. Usually, I sit on his bed waiting for him to come around, but today I took the phone out of his hand and put it on the table.

"What the fuck, I was in the mid—"

"You're on my time now, you can talk to her after," I told him.

He didn't know what to make of it but I didn't wait for him to catch up. I pushed him on the bed and pulled down his basketball shorts. He was still flaccid, but even soft I couldn't fit all of him in my mouth. It didn't take long before I felt him getting hard for me. He put his hand on the back of my head as he liked to do and forced more of himself into my mouth, but that's not what today was about. I pushed his hand off my head and climbed up on top of him. I gave a loud moan as I took him inside me. Even still, it was an effort to work all the way down him. I leaned forward and bit his earlobe and whispered, "The next time you fuck her, I want you to think of me."

He looked taken aback at what had gotten into me, but he didn't fight it. He grabbed my hips and started bouncing me on his big cock, "Is that all you've got?" I said lightly while I smirked down at him. He started thrusting harder and I loudly moaned "I want you to think of me!". As he was pounding away under me, I grabbed his chest, thinking of how much I'd rather have a handful of Kelse, "Fuck they're so big, I want it," I moaned. "Come on baby, I want you to think of me," I loudly moaned again.

I ran my fingers through his hair and gently said "I want you to get behind me, you owe me for Friday." I gasped as he quickly pulled out and bent me over, my head right against Kelse's wall, right where I wanted to be. "Yeah baby, I want you so bad," I said as he pushed himself back in me. "Oh fuck, baby! I'm so wet thinking about you," I moaned into the wall. He rubbed his hands up my back as he gently thrust behind me, I turned back to look at him in the eyes and said, "Fuck me like a man; if I wanted a boy I'd find some dude at school."

He seemed to take that personally and fucked me like I wanted, it took everything I could not to actually scream. "I want you to cum for me," I yelled into the wall, "I want you to think about me every time you cum." Chad's balls were slapping my clit and I knew I was getting close, I moaned, "Come on baby, come with me." I reached between my legs and rubbed myself, just like how I hoped Kelse was doing on the other side of this thin wall. I twerked my ass against Chad's hips as I came on his big cock. I finished before Chad did so I stayed bent over for him to finish. He finally stopped thrusting and I could feel his cock pulsating as he came inside the condom inside me, a cumseption, and pulled out.

Kelse

I lay in my bed, panties wet and head spinning from my unexpected orgasm. Whatever awkwardness I feared was gone. I've never had sex, but this must be what it feels like afterward. I never thought of myself as a lesbian or whatever, but Karin is definitely pretty, and listening to her is really hot, why overthink it?

Just then Karin poked her head in the door. "Is it okay if I come in?"

"Of course, please"

Karin walked over to the bed, lay down behind me, and put her arm and leg on me. I could feel her warmth and we were both a little sweaty but neither of us minded.

"Are things back to how they were before?" she asked.

"Yes. Well... no. I think things are much better."