She had known Marci since their senior year together, becoming close friends and spending a couple middling years in community college as classmates. In that post high school weirdness, where kids become adults and friendships easily disappear, Jill and Marci seemed to have a real kinship. Perhaps it was because everyone else had moved on and out of town, or gotten married and had a kid- but the two young women were close.
Jill had watched Marci meet Adam, and eventually accepted him, but she couldn't help but feel a pang of jealousy. At first it was because of her third wheel status, but then she figured it was at the possible loss of her best friend. When Marci had approached her about the threesome, she wasn't entirely uninterested- but wasn't all that attracted to Adam or keen on the idea of being used by some idiot man child. But she could see her friend was desperate to find a friendly, trusted third. And while she was dismayed at how much Marci wanted to please her man to keep him around, Jill too wanted to please Marci for similar reasons.
But when the three were finally behind closed doors, with clothes coming off- something else triggered Jill. She had really enjoyed taking off Marci's clothes, seeing her friend's body in the raw, up close and in a different context. It was as if Adam's sexualized gaze and Marci's wanton posture had awoken something within her.
She surprised Marci at one point, when she was removing her bra and found herself gently caressing the side of her breast, before tracing her fingers along her ribs and resting on her hip. It was an accidental sensuality that caused Adam to improvise, his quiet voice suggesting the two ladies kiss. Girl on girl was not discussed as part of the play beforehand, nor was it part of the worship. It was generally accepted that bodies would touch and mash into one another, but at no point in time were the ladies expected to perform.
The girls had looked at one another, apprehensive but also trying not to look too eager. In some respects both had wanted to get it over with as soon as possible so they could move on. But the moment their lips came together, Jill had felt as easy as breathing. Marci's lips felt soft and full, and for all their worry both women instinctively used their tongue.
Breaking the kiss had them stare at one another in a longing disbelief, much like they were now- with Adam noisily starting the shower.