Tom

"I'll get her", I said, grabbing her drink and going upstairs. As I got closer to Sam's door, which was closed, I listened and stepped back, shocked, at the unmistakable sounds of moaning coming from inside. Was she masturbating? My hand faltering, I knocked. No, she probably wasn't. I'm hearing things. "Sam, Kate and I are having cocktails, we poured you one, do you want it?".

"Oh, just a second", came the voice from behind the door. Objects being set down, possibly knocked over, and Sam opened her door. She was wearing a sundress like Kate's, perhaps even shorter, and leaving little to the imagination. Again no bra - it was too hot for that, I guessed. Her hair was messed up and her cheeks flushed. "Yeah, let's go down". She didn't meet my gaze as she went down the stairs, and as she did, I caught a glimpse down her dress at her breasts. This was going to be a great house share.

"Having fun, Sam?" asked Kate, still sitting on the table on the kitchen. There was a tone to her voice - Kate was clearly teasing her. Sam nodded, and picked up her drink. She wasn't rising to the bait.

"Hey, this is good, what is it", Sam asked.

"It's called a 'Between the Sheets'", I replied. "Cognac, Rum and Orange Liquer, they're one of my favourites."

"Do you like it Between the Sheets, Sam?", asked Kate, jumping from the table, "Or are you happy with your own handiwork?"

"Shut up, Kate". Sam was trying to pretend to be annoyed, but her blushes and grin were obvious to everyone. She WAS masturbating, I knew it! I said nothing, not wanting to offend anyone on my first day.

"Oh, I'm sorry, Sam. Didn't mean to embarass you.", Kate kissed Sam on the cheek playfully, letting her hand slide across her back. Was it my imagination, or did she slide it over her ass as she did? If she did, Sam didn't react. Girls do that to their friends, I guess. I thought back to my college days, and watching my housemates make out as dares and when they were drunk. Occasionally they'd get overexcited. I guess for a bi girl, kissing someone to turn on a bunch of guys is pretty hot.

Kate moved to sit on the table behind Sam's view, caught my eyes and mimed masturbation. Catching my eyes widen, Sam turned and instantly flew at Kate to tackle her. "Shut up!" she said, as Kate fell to the ground, Sam on top of her, pinning her arms down. Sam, who'd also changed into a sundress, was pinning Kate down. Kate, as the bigger of the two, was clearly letting her, writhing around undernearth her as they fought. Sam's dress rode up, exposing her black lace boyshorts under her dress.

Should I intervene, or watch?