The next morning started off a little different than previous mornings. Ali in bed with me wasn't a new thing. Waking up, both of us naked, was.
We were nestled together, spooning, her back pressed against me, my hand resting against her belly. I felt a surge in my cock as my morning erection began to grow, and I ran my hand up along her skin, grazing her breast.
"Mmmm." Ali purred as she stretched, starting to roll onto her belly.
My hand brushed her skin, tracing around her ribcage and onto her back, trailing down to her ass as she prostrated herself on the mattress and rolled her head to face me, pushing her hair back out of her face.
"G'morning," she said, laying her head back on the pillow.
"Morning," I said, leaning over and kissing her.
Ali sat up with a start, looking at the clock, and then flopped back down.
"I was afraid we might have overslept," she said.
I turned to look at the clock.
"We've got plenty of time," I said.
"I know," Ali said, rubbing the sleep from her eyes. "I'm gonna go take a shower."
Ali kissed me again as she climbed over me and skipped out of her bedroom.
I rolled over in the bed, my cock throbbing with early morning zeal. I took a couple of deep breaths and crawled out of bed.
I looked down the hall, rewarded with the sight of Ali bent over adjusting the water, her ass thrust back at me. A moment later, she pulled the shower curtain closed.
I went to the kitchen to find something to eat, and as I walked out of the kitchen, my erection swayed in front of me, refusing to go away.
The events of the day before were still a rush in my mind, and I couldn't escape the thought that I would once again be naked with Ali, in front of a woman I barely knew, for most of the day.
What sort of posing would Lisa want us to do? Would it be as sexually charged as yesterday afternoon had been?
I closed my eyes and wrapped my hand around my cock, beginning to stroke gently. I couldn't shake the image of Ali's gorgeous ass, and I knew if I didn't do something, I'd start the posing session with a massive hard-on.
"What are you doing?"
My eyes snapped open to see Ali standing in the doorway to my bedroom. She held the towel just in front of her, but I could still see her breasts pushed up against her arm.
"I... "Caught masturbating by my sister, I couldn't find words.
"I mean, I know what you're doing," she said, stepping into the room and walking over to my bed. "But why?"
Ali sat down beside me on the bed, dropping her towel. Her fingers grazed my cheek as she kissed me softly on the lips. Her hand fell to my lap, taking hold of my cock. Her thumb rubbed over the head.
"If I don't," I said, "I'll be hard when we start this morning."
Ali kissed me again.
"I don't care," she said. "And I don't think Lisa does, either."
"If she has us pose like we did yesterday afternoon..." I said.
"If she has us pose like we did yesterday afternoon," Ali said, "you being hard won't be a problem."
"Remember how horny we both were?" I asked.
Ali bit her lip, nodded and smiled.
"And if we get to that point again..." My words trailed off.
"We'll... have to take care of each other again."
"You're not worried about her seeing us?" I asked.
Ali shook her head.
"I got to thinking about it while I was in the shower," she said. "I'm pretty sure she saw us."
Ali leaned in and kissed me, nipping at my lip.
"And she didn't say anything," she said. "So..."
"So?"
"So, I don't think she minded," Ali said. "And besides, it's not like we meant for her to see us. It'd be different if we actually had sex in front of her.
"You know," she said, "if we were actually having sex for her to draw it or paint it. We just have to be more careful."
Ali's hand slid slowly up and down my cock.
"You keep doing that," I said, "and you're gonna make me cum."
Ali stopped.
"I'll make you cum," she said. "Later." She stood up, turning to face me, sliding between my legs.
"Just promise me one thing," she said. She was standing near enough to touch, my cock pointed straight at her pussy.
"What's that?" I asked. I reached out and rubbed her thighs.
"Come to me when you want to..." she looked down at my cock. "When you're hard and you need to cum, let me know."
"Ali..."
"If we didn't have to get ready to go," she said, "I'd finish you now."
She leaned in and kissed me on the cheek.
"And I promise I'll take care of you one way or the other today," she said. "But right now, you need to grab your shower."
When I came out of the shower, Ali was walking down the hall naked, coming from the kitchen.
I was dressed in a couple of minutes, and when I leaned into Ali's room, she was still naked.
"You gonna get dressed today?" I asked.
"Bra or no bra?" she asked, turning around and cupping her breasts in her hands. "Seems kind of pointless when I know it's coming off as soon as we get there, ya know?"
"So don't wear one," I said.
"You'd like that wouldn't you?" she asked, walking over to me. "You'd like to watch my boobs bounce up and down beneath my shirt, wouldn't you?"
I nodded.
Ali smiled at me and turned to her bed. I watched as she pulled her hair back into a pony tail and then pulled a t-shirt over her head. Next, she pulled on a scant pair of bikini panties and reached for a light skirt that I remembered hit her mid thigh.
"You wanna pull my panties off me again today?" she asked.