It was one of those hot summer afternoons when the air felt thick, and all I wanted to do was lie down on the couch with a fan blowing right in my face. My parents were away at a business conference for a few days, leaving my stepbrother, Mike, and me home alone together.

I had just returned from grocery shopping and was carrying in bags when I noticed the bedroom door slightly open. Curious, I set the bags down and peered inside. There he was – Mike, lying naked on his bed with a hand wrapped around his cock.

My heart raced as I watched him slowly stroke himself, his breath quickening with each thrust of his hand. His eyes were closed, completely unaware that I stood there, mesmerized by the erotic sight before me.

I couldn't help myself; I had to touch my own pussy while watching him pleasure himself. As I slid a finger between my wet folds, I felt a shiver run down my spine. This was so wrong but felt so right at the same time.

"What are you doing?" Mike suddenly gasped, his eyes flying wide open as he spotted me standing there, rubbing myself shamelessly. My face flushed red with embarrassment, but I didn't stop touching myself – in fact, it only made me more aroused.

"Watching you," I admitted breathlessly, my voice barely above a whisper. His eyes locked onto mine as he continued to stroke himself, his grip tightening around his cock.

"You like watching me?" he asked, his voice rough with lust. I nodded, unable to form words as I watched him play with his erection. He slid his hand up and down the length of it, spreading pre-cum across the swollen head before dipping lower to tease his balls.

"Show me how you touch yourself," he demanded, staring intently at my pussy. My knees felt weak as I reached for my clit, circling it gently with a fingertip while watching him pleasure himself.

Our eyes never left each other's as we masturbated together, our breaths growing ragged and uneven. He picked up speed, his cock throbbing in his hand as he neared the edge of climax. I could feel my own orgasm building, waves of pleasure crashing over me with every stroke of my finger.

"I'm going to cum," he groaned, squeezing his eyes shut tightly. His cock pulsed violently in his hand, and a hot stream of cum shot from the tip, landing on his stomach and chest. The sight was too much for me to bear; I cried out as my own orgasm ripped through me, waves of ecstasy washing over me like a tidal wave.

We lay on his bed, catching our breaths and basking in the afterglow of our shared pleasure. As the sun began to set outside his bedroom window, I knew that this was an experience we would never forget – and one we will likely explore further.