Ty woke later, and needed to go to the bathroom. He got up, and went to the en suite he'd previously created for Lisa. When he got back, he saw Lisa back in her human form, and she said, "my turn."
When she came back, she asked him, "Want me to let you in on a little secret?"
"Sure!"
"There's one of me in your cock."
Ty was surprised, as he hadn't transformed her into his cock since some time before she was grounded. "How is that possible?"
"Well, when I discovered that I can duplicate myself..." she started to explain.
"Yes, you surprised me with that too!" Ty said.
"Well, when I was in your cock, before, and you duplicated your cock, that duplicated me, as you know. And because you've given me the power to undo and redo transformations you've done to me, it occurred to me that I could probably do that in any form, not just when I'm your cock. So I've been doing that a lot over the past week, being in multiple forms, fucking myself on top of my mattress topper form, and being that and humans and kittens all at once. Though through all of it, I was disappointed that I only had myself, when I wanted you."
"That's interesting," Ty said, "because I did some of the same stuff. Though not the kittens. But I was dissatisfied. I could get off, certainly, but it was just fancy masturbation. But anyhow, about you being my cock now?"
"Well, the first day of being grounded, I passed by you in the cafeteria, and that got me to thinking. I wasn't sure if it would work, and it might have been pretty embarrassing if something had gone wrong, but the next time I walked by you, I duplicated myself, and simultaneously transformed the duplicate into your cock."
"I thought I felt something funny in my groin as you passed by, but I didn't know what it was," Ty said. "So I just assumed it was just being horny, or even just my imagination."
"No," Lisa said. "I'm pretty sure it was me. And I've been there all week!"
"But... but we weren't supposed to see or talk to each other!" Ty said. "You didn't stick to the consequences we agreed to with your parents!"
"Yes I did," Lisa said. "The me in your cock didn't see or talk to you, and you apparently didn't see or talk to that me, either."
"Well, I guess so," said Ty. "But it still seems to have violated the spirit of what we agreed to."
"I did it on a whim," Lisa admitted, "but when I've thought about it afterward, I really believe that I haven't broken my word.
"Incidentally, I also thought about turning copies of myself into other guys' cocks at school, but I didn't do it because I wasn't sure how I'd handle transforming them back. And being other guys' cocks hadn't actually worked out so well for me the last time."
"Well, perhaps you haven't broken your word," Ty said. "I guess I'll have to think about that some more. But I'm a bit upset with you for doing that to me secretly, without my consent."
"You previously agreed to put me into _every_ man's cock, over four billion of them, without their knowledge or consent," Lisa countered. "What's one more? Of course, that was a disaster, and I didn't enjoy it at all, but I'll bet that I've enjoyed this week."
Ty thought about it. "At the time, you convinced me that it was OK to do that without their consent, because they'd never even know. Maybe I didn't think about that carefully enough at the time. But now that I've been on the receiving end of it, I think maybe that isn't such a good argument after all."
Lisa said, "Why don't you transform Ty's-cock-Lisa back into a human Lisa, so we can ask her about her week?" Ty nodded, and a second human Lisa appeared in the room. "How was your week?" Lisa asked herself. "Most of it wasn't too exciting," formerly-cock-Lisa said. "Ty didn't fuck or masturbate nearly enough during the week, though there were a few pretty good times, especially when he duplicated himself, and unknowingly, me. But in cock form, pissing and even just sleeping are nice too, so I had a reasonably good time. But today... today was completely fucking amazing! I don't know how many of me you made, but I have memories of a zillion me fucking a zillion pussies, all now merged back together into me! I want to do that again!"
"That's specifically why I had Ty do that today," Lisa said. "Previously, when Ty said that he didn't think he could have as many cocks as I wanted, it gave me the idea to be four billion cocks, every man's, and at any given time some number of them would be fucking or masturbating, and I'd have gotten a lot of enjoyment out of that. Well, I didn't get us any enjoyment from the four billion that way, because of how it ripped me to shreds, but today I got us over a hundred million, and all fucking at once, so that should be even better than the four billion would have been. Now I want to have the experience of that. Let's merge and share our memories, and then, if Ty is OK with it, I'll duplicate a me back into his cock."
Ty started to object, but formerly-cock-Lisa beat him to the punch. "I don't want to merge. I'm happy with just my memories, and I just want to go back to being Ty's cock."
Lisa and Ty were both surprised, and uncertain how to proceed.