"... I'll do it." Megan said softly, her face reddening as she thought about what she was about to do.
Amy's face went from surprised, to confused, to utter glee in only a fraction of a moment.
A brief disorienting swing followed, then a sudden drop, as Amy turned around and plopped down on the couch next to the chair Megan had just been sitting in.
Amy settled in, each little wiggle, twist, and turn jerked and swayed Megan, effortlessly and incidentally.
She was moved, put down to sit on Amy's still clothed stomach, and looked up at her little sisters face.
She was still smiling, now flushed and breathing heavy in anticipation, her head raised by some pillows, looking down her own body,
There, on her very body, her 1'4" 'big' sister sat, naked and at her mercy.
She ogled Megan, Amy's grip prevented her from covering herself, in fact, the sheer difference in strength meant Amy wasn't even sure she made an effort to do so.
"Say it ." Said Amy, who let go with one arm, and started running a finger almost the size of a whole arm through Megan's hair.
"Say you want to go down on me." Her smile grew and she let out an audible chuckle as Megan was hit by the shock.
She hesitated, but there was no way she could draw this out long enough for their parents to come home, and she swallowed her pride.
"Please may I eat you out." If she could have turned any redder, she definitely would, as she continued. "I- I wish to please you, mistress."
Amy went from slightly flushed to fully red, bit her lip, and let out a soft, long, moan.
Her hands let go and moved away from Megan, who fell backwards on Amy's lap, as the tween removed her shirt, revealing her training bra, followed by being tossed to between Amy's legs as the removal of the giant white panties easily threw her off her footing.
As she gathered herself and looked up, she could see the last of the movement of Amy removing her bra, dropping it on the floor.
Amy settled back into the couch, and she started playing with her budding breasts, her eyes locked back onto Megan, eagerly awaiting 'lip service'.
Megan looked down to between Amy's giant thighs, a glistening, pink crevice, covered by a forest of thin, frizzy hairs.
As she crawled forward from between Amy's knees, and as she came close enough to feel the heat, she slowed down, starting to feel...
Intimidated.
The cavity could easily swallow her head, and if Amy said shrink one more time, here whole body.
Every wiggle and shake Amy made while playing with herself were violent shakes and grand movements for her, and her cunny was starting to moisten.
Amy was still watching Megan with great interest, slowly losing her patience with the tiny woman.
Maybe she should say shrink, and stuff her in entirely for making her wait, even if only for a few seconds.
Or maybe she could make her grow a little, a little encouragement for being a good girl...
Amy let out a surprised yelp.
Before she could make her choice, Megan had made hers.
Taking a deep breath, she pressed her face onto Amy's womanhood, her tongue lapping at the engorged clitoris, as her left hand worked the outer folds and curtains, and her right arm thrust into the glib, muscular debts of her sister's slit.
Her mouth filled with the taste of Amy's arousal, sweat built from a hot summer day, and grime and urine from a tomboyish lack of hygiene.
Her skin chafed by the coarse fuzz and rubbed raw by the rubbery skin as Amy bucked and twisted.
Her arm tugged, clamped, and kneaded by the walls of her little sister's cavern.
For the next ten minutes, this was Megan's world, and she grew disheartened as she realized how much power Amy had over her, just from a few injections.
"More! More!" Amy stammered, with little control over the volume of her voice.
The bucking became more intense, and Megan started to lose her grip, and started to get concerned, sure she would be punished if she couldn't bring her to orgasm.
Without hesitation, but some reluctance, she stood up, and climbed onto her sister's twitching body, and, with the frizzy bush underneath her, laid down on her stomach, reaching her head back down between Amy's thighs.
Awkwardly, she reached her left hand, now massaging and squeezing the burning love button, as she lowered herself down, her right hand feebly keeping her from falling, and resumed licking, kissing, and nipping at Amy's folds.
A heavy weight landed on Megan's back, a hand holding her in place.
Taking the opportunity, she had her right hand free to join in.
The movements became more intense, the pressure on Megan increased as Amy's muscles tenses.
It took another five to fifteen minutes, Megan was beginning to lose track of time, but she was suddenly shot upwards, as Amy arched her back in climax, still held in place  by Amy's iron grip, freed as she came down, her face moist with her little sister's love juices.
Amy laid on the couch, catching her breath, practically purring, mentally gloating.
Megan still laid face down on her pubic mound, looking away from Amy.
"You've been a good girl. Or a dirty slut." She said, as she pinched Megan's cheeks, who let out a short yelp in surprise and pain.
"Thank you, mistress." Megan meekly replied, sitting on her knees, still on Amy's bush, still avoiding looking at her.
Amy smiled at the thoughts and feelings that were no doubt going through her sister's head.
With little ceremony, and as sudden as she could muster, she got up, causing Megan to fall and crash into the couch.
She gathered her clothes, and Megan's too, for good measure.
"Later, slave girl." she said, lightly sniggering, as she left her sis- no, plaything, behind, and started moving towards the stairs.
Megan got up. "W-wait!" but she was ignored.
She got up, or rather, dropped down, from the couch, and attempted to keep up with Amy.
Even with her shrunken strides, she could almost keep up with the casual stroll her sister had put up.
Until she got to the stairs.
Each step reached up to her knees, and she couldn't even hope to reach the railing at this size, and climbing a the same speed as Amy walking was nothing but wishful thinking.
By the time Megan got to the second floor landing, Amy had already reached her room on the third.
Stopping to catch her breath, she pushed through and started to climb the next flight of stairs.
Amy's door was open, and she ran as fast as her tired legs could carry, fearing Amy would close the door at any moment, dreading she would close it in her face for laughs.
She didn't, and as she reached the door frame, she could see Amy had already had time to put on a nightshirt, sitting on her bed, fiddling with her phone.
"You followed me. I don't remember telling you to follow, -" She said, turning to the 16 inch woman. "- but now you're here, come over." She pointed at the floor, right next to her bed.
Megan gulped, and started to approach the 20-something foot girl, and as she reached her, a hand descended upon her.
"Shrink."
The world expanded as Megan shrunk to 4" tall, still held in Amy's hand.
The grip adjusted, and Megan was held high and tightly, her breasts resting on Amy's fingers, as she was drawn closer to her face, and made to face the camera of Amy's phone.
The image of Amy pulling a duckface, holding helpless little Megan not an inch away from her face, greeted her, as Amy made a selfie.
A selfie celebrating Amy's domination of her not-so-big sister.
She was dropped, right next to Amy's hips, as the now 80 foot tween returned to her phone.
"Now then." Amy said, putting the phone on her nightstand, now looking down at Megan. "What brings you here, togygirl?"
Megan was lifted up again, but was allowed to sit down on Amy's open palm this time, faced with her sister's titanic face.