(A note for readers: Grandpa isn't a nice person; he wasn't meant to be. I may write a story with a nice grandfather, but do remember that this is a STORY, and that the characters are not real.)
Jenny did model the outfits for her mom. Well the three from the mall, anyway. Her mom complimented her on her taste and then headed to her room for a nap.
"Time to model for me, pet," her grandfather said as soon as her mom was in her bedroom. "Put on the red one."
Jenny had hoped for some time for herself, some time to enjoy her new clothes, but she knew she had to do what grandpa wanted. "OK," she said reluctantly.
"And strut like you're on the catwalk when you come out," he said as his pet went to her bedroom.
Jenny came out strutting as best she could, shifting her hips from side to side like a fashion model, and swinging the peignoir open to show the lace panties, bra, and garter belt she wore.
"Nice," grandpa said, "now turn around a few times, and then slide the gown off your shoulders for me."
Jenny complied, and grandpa began again. "Now bend over towards me so I can see how your tits hang in the cups."
"Very sweet," he said, whistling obscenely through his teeth, "now shake them."
His pet did as she was ordered, but she felt humiliated, like she was some kind of slut who had to... "I guess that's what I am anyway," she thought to herself.
"Come here, pet," he ordered, and she started to stand upright.
"No, stay bent over, just shuffle your way to my chair."
Jenny shuffled, realizing he wanted her breasts to continue to jiggle as she went to him. She stopped at his knees and stayed bent.
"Hands behind your back, girl," he said, "let's see how hard your mouth can get me by itself."
She took a deep breath of resignation and brought her lips to the tip of his flaccid cock. How was she to get it in her mouth if it was just lying there, she wondered. She kissed it a few times, and then began to lick it. It perked up a bit with each stroke of her tongue, and when she could get the head between her lips, she sucked it into her mouth.
She sucked hard, and the old man's cock stiffened more and more.
"That's a good girl," he said patting her head as her lips slid up and down his shaft.
He was as stiff as a teenager now, and he ordered her to stand up and turn around.
"Pull your panties to the side and slide onto my dick, pet," he told her.