There's a lesbian who's repulsed by cocks and she knows this makes her a bad ally, so she asks me to help her get over her aversion through exposure therapy.
It starts with getting her more comfortable with just looking at one. So of course she gets to sit and watch me stroke it, doing her best not to look away as I slowly pump my hand up and down my shaft. When she looks up and meets my eyes it's clear I'm using her as jerkoff material. She figures the quicker I cum the better, so she starts wearing short shorts and low-cut tops to show off her body better.
She still thinks cocks are gross, she still feels a shudder of revulsion(?) when she thinks about one fucking her, but at least she can look at one without freaking out.
I start sending her unsolicited dick pics during the day. Somehow looking at a picture is easier, and if she happens to glance at them while she's playing with herself, well, that doesn't mean anything.
It's still gross, but she can at least sorta stand facing down a cock, so we move from having her watch me from across the room to up close, kneeling in front of me while I jerk off over her. It's so different, seeing my massive girldick looming over her face, twitching, leaking pre...she gets to inspect every inch of it, see every vein, get up close to my heavy girlballs, even smell it. The thing is, I don't give her a warning before I cum all over her face.
By now she's masturbating to my dick pics every night and she buys a dildo the same size as my girlcock to trains herself on. She still can't quite make the whole thing fit but sometimes she just rubs her clit while sucking on it.
After that we move on to touch. There's still just a part of her that feels revulsion, but I'm patient, showing her how to stroke it and murmuring encouragement, reminding her to fondle my girlballs, too. She can take as long as she needs, really get used to the way it twitches and throbs in her hand. At this point she's almost looking forward to me cumming all over her face, last time she got a little on her lips and licked them clean without thinking.
Finally, something in her breaks. Maybe it's the realization that her cunt is leaking while she jerks me off, maybe it's the fact that her dildo can't match up to my hard, hot shaft anymore, maybe it's the taste of cum. She loves girlcock, she can't get enough of it. She learns to worship it, planting sloppy kisses and licks on every inch of my shaft, licking and sucking my heavy girlballs, taking my whole length in her mouth on the first go - such a good girl, she's been training for this, and she feels her pussy clench as she presses her lips against the base of my cock.
Finally, she lies back and spreads her legs, but there's still a thread of resistance. She thanks me for being so selfless and helping her through this, but she really can't let me put it inside. Instead, she'll let me tease her clit with the head of my cock, rub it against her pussy lips. She finally realizes what it feels like to have a girlcock pressed up against her pussy, and she wonders why she ever could have been afraid of this. That final thread snaps, and she's the one who makes the final move. She wraps her legs around my waist and pulls me inside her. She's ready to be totally and completely claimed by girldick.