Me and my brother are very close and have never been shy to talk about masturbation, we both love this site and I come on it every day religiously. My brother (Tom) is a just a bit older than me and has quite a great body as do I.
One afternoon I was on my bed reading some of the stories on here using my laptop and Tom was in his room on his PC, his door was closed I presumed he was listening to music with his headphones since I could hear anything.
After reading quite a bit I was extremely horny and was about to go have a bath (with devious intensions), when I realised that Tom had been completely silent for ages, I went over check if he was alright. I couldn't believe what I saw!
Tom was sitting back with his eyes closed massaging his dick and moaning lightly, he had his headphones on but it wasn't music he was listening to, that's for sure. Normally I would've closed the door and walked away but I was just so bloody horny and seeing that had tipped the scales, I watched him for about five minutes until I was so wet I couldn't take it anymore!
I walked over too him, knelt down and removed his hand. Straight away he opened his eyes and before he could speak I put my hand on his lips, smiled and said, 'Let me give you a hand'. He put his head back and closed his eyes and I placed one of my hands around his dick and started pumping rapidly, the other I put up my skirt, pushed aside my panties and rubbed my pussy hard and fast. Suddenly he started groaning loudly and a huge spurt of cum came out of his cock and covered my hand, the thought of giving my brother an orgasm instantly gave me my own and I screamed out loud and spasmed on his floor covering the carpet in my juices.
He smiled and said 'Thanks, I owe you one' and then he went to the bathroom to get cleaned up. I lay on his floor panting and after a while went to have my bath, (which I enjoyed very much).
After that I seemed to walk in on my bro 'accidentally' quite a lot. Maybe I'll tell you how he repaid me someday ;)