Localized possession

The outfit Jane collected up folded itself up nicely again. "Actually, I won't need this. I know how to convince you to play along!"

"And how's that? ...Jane?" The trouble with invisible girlfriends who can phase through solid objects is not knowing where they were at any given time. This was going to be a mess, though... you just knew that Jane was going to take this too far.

Your suspicions were confirmed a few minutes later, when Jan walked through your door--but not in any way that a normal human might. Instead, it was almost like she was trying to step backwards, but she was being pulled forward by...

...Some truly enormous breasts.

"Hey, John, look what I can do! I guess the same rules apply like when I'm in clothes, I can change shape and sizes! It's kinda like I made Jan into my clothes, isn't that neat?"

Jan looked at you in total shock. "I... I don't... I don't know what happened, a voice asked me if I wanted to get my chance with you and asked if I was willing to pay the price, and I just said yeah because, well, why not... I swear I don't know how any of this is happening, I'm so sorry John! I don't mean to get in the way of you and your fiancee!"

You gave Jan a serious look in return. "Trust me, you aren't. She's the one inside you right now, manipulating your body to her will. Long story, though if Jane intends to stay put in you then I suppose I'll tell it. Unless you want to go home right now, in which case I'm going to strongly insist to my soon-to-be wife that she shouldn't lead people around by their tits!"

"Aww, c'mon, this'll be fun, don't be like that! We're all gonna have a blast together."

Jan started to yelp, as her breasts began bouncing up and down, seemingly on their own. Jan's tank top was really straining hard at the enlarged breasts, and they showed everything--including what looked like hand imprints against her breast flesh, like Jane was literally gripping Jan's body from within! "N-no, I... I'll be fine, I said I would... just... what is going on, John?"

You recalled the whole story of Emilia and the Ghost Machine to Jan, all while Jane played with her form from the inside. From her dancing breasts, Jane took a detour south and spread her ghostly presence into Jan's hips, widening them and shaking them back and forth, tugging Jan along still as the poor girl couldn't help but step backwards with each tug. At times, the handprint-shaped indentation became visible through the yoga pants on Jan's body, the fabric stretched far enough from the widened hips that the pants had become slightly transparent.

"So... so your girlfriend wanted to use my body to test all this stuff, and in return she is... gonna let me spend time with you?"

"Oh, I'm gonna let you do so much more as long as I'm inside you, honey." Jane was really getting serious about this promise, as her focal point of her possession changed once again. Jan's eyes widened, almost going cross-eyed, as she tried to cross her legs tightly, like she was trying to control some physical urges or sensations she was enduring all of a sudden.

"What's wrong, Jan?" you asked. Throughout all this, you'd mostly spectated, still opting to keep a safe distance from Jan's body. If you tried to help or even tried to touch her, you didn't know how either she or Jane would react. Best to let them make the first moves.

"Oh god, she's... she's inside my pussy..." Jan was absolutely trembling, reaching out to grab the couch as she spread her legs wide, leaning over. You got a pretty clear view of her body, and even if she was a bit on the thin side for you, it was alluring to watch her wiggle and squirm like she was. "It's like she's gone in and started just touching everything..! Oh god..." Jan's fingers came to her crotch, her face red with embarrassment that she was even considering feeling herself up in front of you like this, the guy she had such a strong attraction to. But, your ghostly girlfriend made absolutely sure she couldn't help it..!