Not that much longer

I have no clue how long we actually fucked in total, but in that sensual spoon position, she didn't seem to go as long. After maybe a minute. she stopped thrusting and I could feel her dick throb inside me. "Okay. You feel that? Feel my dick throbbing like that. You know what that means?" she asked. I shook my head, this being my first official fucking and my only experience before that was with my girlfriend and her strapon. "That means, I'm about to cum. Normally, I wouldn't cum inside you since you're my sister, but, 1. despite you being in heat, it's the first day and the likelihood of me getting you pregnant now is actually pretty low. About 12%. and 2. I want to use this experience to teach some things. so..."

Giving a couple more solid thrusts she pushed in as far as she could go, and I felt a sudden torrent of hot liquid begin to fill my womb. This sensation immediately made me cum, as well.

"Good girl. Milk your sister's cock like the horny bitch in heat you are," she encouraged.

She seemed to cum for ages, each little pulse of her cock intiating a mini orgasm. When everything had calmed down, she didn't pull out immediately. "I'm going to leave my cock inside you for a bit. Feels wondeful, don't it?"

"Yeah it does," I admitted, still catching my breath.

"Just having some inside your pussy can help relieve some of the intensity of being in heat. And I've found pulling out too soon can fuck with the brain a bit," she explained.

As we sat there for five mintues she made small talk, "Did that feel good? How's my dick?"

"Ummm...it was great. Wonderful. I enjoyed it. And you're good," I said trying to downplay how much I thoroughly enjoyed the dicking I received.

"Good. I will admit, you have one of the best cunts I've ever fucked. Like a solid 2nd or 3rd. Much better than I ever expected," she replied and after a few more mintues she slowly eased her shrinking dick out of me. While I didn't feel as miserable as before, I was actually disappointed to not have her manhood in me anymore.

Once out, she sat me up, turned me to her and gave me a kiss. "Now, Kate, listen to me," she said, braking the kiss, her furry hands gripping my face. "I want you to take a very cold shower. You're in heat. Heat as in fire. Trust me, it will feel better than those hot showers you love. And a shower, not a bath. I personally knew someone who was in heat, and she took a cold bath. passed out and drown."

I nodded in acknowledgement and got off the bed carefully. "So, you're a sex therapist?" I pried.

"Yup," she nodded. "Well, trying to be. I've taken all the piliminary courses and am in my second year of my actual Sex Therapy course. Not too sure how they'd feel about me knocking up my sister, though. So we're going to try to avoid that."

"Yeah, I don't want mutant babies, either," I agreed.

"That's a myth. But, enough talk, shower," she countered.

I wanted to question her more, but I did need a shower.