For posterity, the high-level scheme I originally had was:

=== ACT 1 ===
> Establishing Futashep as a result of Cerberus meddling, to satisfy Miranda's kinks

> Establishing Futashep regularly fucking her harem of 7 canon ladies (including canon Liara and ME1 Ashley - make the contrast to come more dramatic!)

> On a mission in a club, Futashep gets distracted by a stripper with huge tits

> Liara and Ashley cheer on Futashep as she marathon-fucks the stripper's tits, a feat impressive even by her usual standards

	=== ACT 1 (partial) SCREENPLAY ===
	
	> Waist-up shot of breast-wrapped Femshep sleeping on an operating table.
		FEMSHEP (voice-over): "When Cerberus resurrected me, they wanted insurance on their investment."
		
	> Shot of Illusive Man and Miranda arguing behind sound-proof glass, the sounds of medical equipment filling the soundscape.
		FEMSHEP (voice-over): "Project leader Miranda Lawson wanted a control chip. The Illusive Man himself refused."
		
	> Wrapped Femshep sitting up on the operating table, staring at her huge cock in surprise.
		FEMSHEP (voice-over): "So they compromised. The theory, as Miranda explained it to him, was simple. Elegant, honestly."
		
	> Cerberus-clad Femshep pounding a sex doll, with several others laying around and all overflowing with cum.
		FEMSHEP (voice-over): "A hyperactive libido, left unchecked, would render me effectively inert as a threat to Cerberus."
		
	> A sequence of Cerberus-clad Femshep taking pills.
		FEMSHEP (voice-over): "If Cerberus controls the libido, then Cerberus controls me, she explained. No control chip necessary."
		
	> Femshep sleeping in a small hospital room, with Miranda just out of frame, running her hand up and down Femshep's cock while she slumbers.
		FEMSHEP (voice-over): "The Illusive Man questioned my size. Miranda assured him it was simply a function of her libido control scheme."
		
	> Miranda riding Femshep on the hospital bed.
		FEMSHEP (voice-over): "In truth, she was just a size queen tired of riding inanimate silicone..."
		
	> Femshep and Miranda in a mating-press on the hospital bed, several hours later.
		FEMSHEP (voice-over): "...and eager to satisfy her creampie kink, safe in the knowledge that I could never get her pregnant..."
		
	> After Femshep finishes creaming Miranda, Miranda kisses Femshep then tells her: "breed me again". Femshep obliges.
		FEMSHEP (voice-over): "...regardless of how much semen I pumped into her sterile womb."
		
	> A static-shot slideshow animation of the other female characters appearing one by one.
		FEMSHEP (voice-over): "Over time, my crew expanded. Many were offput by Cerberus' augmentations, but as our bonds strengthened..."
		
	> Fade to black, hold for dialogue, before hard cut to next sequence.
		FEMSHEP (voice-over): "They all came to love my size almost as much as they all came to love me."
		
	> Montage sequence of Femshep fucking the ladies (Miranda, Jack, Ashley [ME1], Liara [Canon], Chakwas, Kasumi, Diana)
		> Man on top
		> Blowjob
		> Unconventional [Miranda thigh-job, Jack flexible, Ashley x Krogan, Liara x Varren, Chakwas femdom, Kasumi pole-dance, Diana bondage]
		> Anal
		> Woman on top
		> Finishers [creampies, cumshots, facials, swallowing]
		
	> As the last finisher fades to black, the voice-over resumes.
		FEMSHEP (voice-over): "I long ago ran out of the libido pills Cerberus used to control me. But with my crew, it didn't matter."
		
	> The black void slides open like scifi doors, opening into a club. Femshep, Liara, and Ashley each take a single step into the club, from behind the camera.
		FEMSHEP (voice-over): "Until one mission pushed everything out of balance."
		
	> Waist-up shot of the three walking through the club, scanning around as Femshep talks.
		FEMSHEP: "Keep your eyes sharp, everyone. We're looking for a Turian. He's--"
		
		*FEMSHEP stops mid-sentence, distracted looking off in the distance*
		
		*ASHLEY and LIARA walk into FEMSHEP, apologizing reactively. FEMSHEP doesn't respond.*
		
	> Ashley and Liara look confused at one another, before asking if Femshep is okay. Ashley waves a hand in front of Femshep's eyes to no effect. The two turn to face what Femshep is watching.

	> A huge-titty stripper is dancing on a pole, with Femshep and the others watching her. Ashley and Liara banter as Femshep stares silently.
		LIARA: "I think we have discovered what has Shepard so transfixed."
		ASHLEY: "I don't blame her. I mean, look at the size of that rack. I don't like girls, but even I gotta admit..."
		
	> A close-up shot of the three looking up. Femshep's mouth is visibly open, her tongue lightly hanging out, as she stares transfixed.
		LIARA: "I have seen busty dancers in my time, but I don't believe I have ever seen breasts so large..."
		ASHLEY: "I can only imagine how sore her back must be all the time..."
		
		*LIARA turns to face FEMSHEP, and her brow furrows in concern*
		
		LIARA: "Commander? Your mouth is agape."
		
		*ASHLEY turns to face FEMSHEP, and uses two fingers to gently push up on FEMSHEP's jaw and close her mouth*
		
	> A close-up of Femshep's erection pushing against her ME3 fatigues.
		LIARA: "Uhh, Commander..? Your erection is... strong."
		
		*ASHLEY brings a hand down and begins to stroke FEMSHEP's erection through her uniform*
		
		ASHLEY: "Mmm. And hard as stone, too."
		
	> Close-up of Ashley leaning in close to Femshep, a wry grin on her face.
		ASHLEY: "You want to fuck her fat fucking tits, don't you, Commander?"
		
		*Hard cut into next shot*
		
	> Sequence of Futashep marathon-fucking the stripper's tits, with multiple cumshots, while Liara and Ashley help, cheer, and support. They comment on how Futashep is going longer and harder than she ever has for them.

=== ACT 2 ===
> After the mission, Futashep shifts from her usual eclectic ways of fucking the ladies to exclusively attempting to fuck them, and getting wordlessly frustrated by their breast sizes.

> Ashley unrelatedly gets her ME3 breast upsize, Futashep immediately goes gaga for them. Futashep proceeds to eagerly fuck Ashley's new tits.

> A sequence of "failed sexy time diversity": different ladies walking in to have sexy time with Futashep, only to find her always distracted with fucking Ashley's tits.

> Ashley complains to the girls that Shep hasn't fucked her pussy in weeks, the other girls grumble that at least Shep's been fucking her tits - they haven't even been getting that.

> Liara disappears on Illium, returns in her Curvy form. Futashep immediately goes gaga for Liara's new tits, proceeds to eagerly fuck them.

> A repeat of the "failed sexy time diversity", but now with Shep obsessed with Liara's tits.

> Liara admits to the girls that she loves the attention, but Shepard's focus is leaving her exhausted. She proposes they need to balance things out, get Shepard's interest equal among all of them again.

> The girls go through group contemplating of all getting implants, weighing pros and cons, before finally agreeing to surprise Shepard on her upcoming birthday.

=== ACT 3 ===
> The girls do a "open your eyes" surprise for Shepard, revealing their new bimbo bodies. Shep goes gaga for them, as they explain they took out a military funding requisition in her name to pay for them, before playfully asking if, since Shepard technically bought those bodies for them, if she wants to try out the merchandise.

> Shepard proceeds to titfuck the girls in the previously-tweeted positions, I'm thinking in an interwoven sequence (one angle each round-robin, back up to the top, rinse repeat a few times; finally ending on 7 cumshots in a row, one per girl)

> The final lady that Shep titfucks coyly asks Shepard if she's happy with her purchases. Futashep playfully replies by picking up one of the receipts and noting that, according to this, she bought them new asses, too.

> Shepard proceeds to fuck the girls in a compositional mirror of the titfuck sequence, but now in positions that emphasize their asses.

> The final lady that Shep fucks asks if she's satisfied now, to which Shepard comments that the ladies used a military requisition - in her name - to pay for the surgeries. And since the requisitions are technically for the benefit of the ship as a whole...

=== ACT 4 ===
> Hackett giving Futashep a medal for new record-high ship morale across the entire ship. Hackett asks Femshep how she did it, and as Femshep is about to respond, camera angle cut to show that this is a televised segment, being played in a room where all seven ladies are being very loudly gangbanged by the crew. The orgy completely drowns out the televised response.

> A sequence focusing on each of the ladies getting gangbanged. Possibly multiple interwoven angles, not really sure. That's a lot of angles to figure out.

> Cut to Futashep casually leaning back and jerking off to the orgy, when Hackett abruptly calls in. Hackett explains that Alliance Command has learned of the inappropriate use of military funds requisitioned in her name, and requires it be paid back in full with interest. Shepard explains that they don't have the money, to which Hackett tells her that Command doesn't care and she needs to find the money.

> Futashep watches the orgy in front of her in silence for long seconds, before J-cutting into a shot of Shep boldly auctioning off the ladies in a one-night raffle, with them on a stage on Omega, as Shep flaunts their bodies to a densely-packed crowd of aliens.

> A complex sequence of Shep pimping out the ladies, with interwoven sequences of a currency counter going up, Shepard pitching sales in various locales, and of course lots of sex with the ladies, with a general focus on bondage and anonymous sex.

> A canon Samantha Traynor walks up to an incredibly bougie / pimp-fashion Futashep, whose watching a sex scene with one of the ladies, and asks how close they are to paying off the requisition penalty. Shepard waves Traynor's concern away, admitting that they paid back Alliance Command several million credits ago.

=== ACT 5 ===
> A confused Traynor asks what Shepard is doing with all the money then, before snarkily muttering under her breath "besides turning our home into a brothel". Shepard admits that's not a bad idea, before eyeing Samantha up and down for a moment and comments that Samantha "wouldn't look half-bad with a rack like theirs."

> Samantha gets flustered, as Shepard calls out to Kelly how many women are aboard the Normandy. A canon Kelly Chambers comes into frame, and hands a datapad to Shepard. She looks at a long moment, before lowering it and watching the sex scene ahead of her, as she says "Yeah. We can afford that."

> Hard cut to black. After a moment of silence, Samantha's voice calls out that a pirate vessel is on approach.

> Hard cut in to Futashep in her captain's chair, telling Samantha to establish communications with them. Samantha, off-screen, confirms.

> A bimbo Samantha Traynor, wearing a hybrid fatigues-and-bikini uniform and heavy glam makeup, turns from her panel to relay to Shepard that they have visual. Shepard tells her to put it on holo.

> A hologram appears of a Turian pirate front and center. Shepard greets the pirate warmly, and asks if he's back for seconds already. The pirate asks how much it would cost to "buy the whores you had sent us previously".

> A stern-faced Shepard bluntly notes that her girls aren't for sale. Her face softens as she continues with, "however, they ARE cheap to rent. I might even be able to offer a discount - let me quickly check with my yeoman..."

> The hologram blips out, as Shepard off-screen asks Kelly if they have any rooms available.

> The first wide-shot reveals a bimbo Kelly Chambers, again in bikini-fatigues and heavy makeup, on her knees eagerly titfucking Futashep. Kelly awkwardly looks down at her appearing omnitool as she titfucks, and explains that unfortunately all of the rooms are occupied. Shepard thanks her, and asks Samantha to return visuals.

> Another wide-shot as the hologram blips back in, and Shepard explains that they don't have any rooms available. "But to make up for the inconvenience, provided your crew are all willing to share her, I can offer you my yeoman here for a quarter off." The pirate counters with half off, to which Shepard follows up with "a third off, and she's yours till the end of the week." The pirate agrees.

> A close-up as Futashep closes the deal. She looks down at Kelly off-screen and tells her to meet her clients at the airlock. Some off-screen shuffling, and a brief view of Kelly walking past Shepard. Shepard calls off after her, "and change into something sluttier!" Shepard returns her attention to the holo: "by the way, I never did ask: how large is your crew, exactly?"

> A close-up of the holo, as the Pirate explains that his crew is about a dozen men strong. He asks if that will be a problem for her yeoman. "Only a dozen?"

> A close-up of Shepard with a smug grin. "Kelly handled more than that just this morning."

> A wide-shot of the Normandy and pirate vessel in space, with a shuttle leaving the Normandy toward the vessel. Shepard and Traynor are heard in voice-over. As Samantha speaks, her voice fades out as the screen fades to black.
	SHEPARD: "Specialist Traynor, where to next?"
	SAMANTHA: "Well, we need to pick up Ashley from that vorcha breeding colony, and Miranda should be finished with that Krogan diplomat meeting. Liara's lease with the Batarians should similarly be closing out by end of day today, and..."