Kate

"I'll get her, don't worry", Kate jumped off the table, grabbing the drink and disappearing upstairs in a flash. I heard her footsteps and the muffled sounds of talking upstairs as she left.

A minute or so later, they both arrived. Sam blushed as she came downstairs holding her drink.

"What's up?", I asked, noticing her red face.

"NOTHING", Sam shot a look at Kate, who broke into fits of giggles as she came down. "It's NOTHING, isn't it Kate?". Kate was entirely failing to hide her laughter at her flatmate, and smirked knowingly. "No, don't say a word".

"Oh, I'd never embarass you, Sam", 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?