After tucking it into the pit of my arm to warm it up a little bit, I got to my knees, too. As Donna and I looked at each other, I told her "Sweetheart, I am not going to do anything to make this happen. I know you want to try, but all I'm going to do is push myself against you so that it can happen — it's going to be entirely up to you whether or not it actually does. I'll stop any time you tell me to, and even back off if that's what you want, and start again when you tell me to.
You said you wanted me to help, so that's what I'm going to do — help. It's your choice about how and when, or even if, it happens. Okay?"
"I understand, Uncle Ted. I'm nervous about this, but I'm not afraid, or anything."
I leaned forward enough to give her a soft kiss; when our lips separated, she didn't have anything else to say — she just calmly leaned forward until she was on her hands and knees. I moved behind her, and immediately ran into a problem… I couldn't hold the bottle of oil, apply it, and separate her cute butt cheeks all at the same time due to a shortage of hands. I told her what the problem was, and heard her laugh before she said "This problem is something I didn't think about…", causing me to laugh with her. After she lowered her shoulders to the bed, she was able to reach back and spread her cute fanny for me; it took only a few moments for me to get the oil (up to body temperature by then) opened up. After pouring some into my palm, I moved my hand to the top of her ass, then carefully poured the oil so that it ran down and across the pucker of her anus. Using just a single finger, I spread the oil around … not just covering her rectum, but a good distance out from it, as well. Another ration of oil was similarly applied, and I began patiently and gently working it farther and farther into her. After dispensing another puddle of oil and adding it to what was already there, I was able to carefully work my entire finger into her bowels. When I'd gotten one last batch of baby oil worked through her pucker, I used what was left on my hand to coat the outside of my erection.
That was when I realized I'd forgotten something else — a towel or something to wipe my hand off with. Once again, I pressed a corner of one of my sheets into service; after I'd wiped the surplus off, I told Donna "Okay, honey, I've got oil on me, and you're oiled up, too."
"I guess! It feels like you used the whole bottle!"
Teasing her, I asked "I figured too much was better than too little. You want me to clean some off?"
"Not if you want to do this, too!", she responded, teasing me back.
Taking my erect cock between a couple of fingers, I levered it down and moved closer to Donna; it took only a few seconds for me to get the head softly wedged against her most intimate orifice.
Pressing against her just enough to keep my cock in place, I told her "When you tell me you're ready, I'll start pushing against you. If something happens and it doesn't work, don't worry about it — we'll just try again, unless you say not to. As long as I can feel you trying to let me in, I'll keep pushing against you… but not too hard."
A few seconds passed before I heard her say "Okay, Uncle Ted, I'm ready. You can start whenever you want."
I slowly increased the pressure I was applying to her sphincter until I could feel it starting to open up to me, then held the force I was applying steady until I either felt Donna open herself to me more, or she told me to stop.
When I'd kept that steady pressure against her for several seconds, I could feel as Donna tried to relax herself to me; initially, it was a lot of back-and-forth between feeling her open herself to me, and having her lose whatever progress she'd made. But as the seconds ticked by, she gradually changed over so that she was relaxing herself to allow me entry more than she was preventing it. Slowly, barely a millimeter at a time, I could see the head of my cock slipping through the tight portal of her rectum. With each advance, I applied a trifle more pressure to protect our gains; but I was always careful not to say or do anything that might make her think I wanted her to go any faster than she was comfortable with.
I think both of us were surprised when we felt the glans of my manhood was all the way inside her, so that her anus was clamped around me right behind it. When that happened, I immediately stopped what I was doing so that I could hold myself still in her until I found out what she wanted to do.
A few moments later, I heard her tell me "That it, Uncle Ted — just hold still like that. I thought your penis was big before, but now it feels absolutely huge."
"Are you okay, dear?"
"Oh, I'm fine, Uncle Ted. I'm not hurt or anything, it just feels weird having you inside me like this. Sexy, but weird."
I could feel her gradually relaxing (at least, as much as she could) around me; with the realization that the hardest part was over, she was starting to learn to accept being opened up that much, and that way. She released her hold on her ass cheeks, and got herself back on her hands and knees before telling me "You still feel real big, but I'm getting used to it, now. If you want to keep going, I'll let you know I need you to stop or anything."
Getting my hands on her hips to help hold her steady, I slowly began to try and press myself farther into her; when it started to happen, Donna moaned — causing me to immediately stop what I was doing. A couple of seconds later, I heard her plaintively ask "What did you stop for?"
"You made a noise, and I thought maybe I was hurting you.", I explained.
"No, you weren't hurting me. It felt good, so if I made any sound, it was because I liked what you were doing. You can keep going, honest."
I took that as my cue to try again; as I started to slide farther inside her, I heard another moan.
After what she'd told me, I was able to recognize it as a sound of passion, and not pain; I just continued to ease myself farther and farther into her bowels. I only had to stop when my pubic hair was wedged into the crack of her ass, and my balls were grazing her mons.
It seemed to take a few seconds for Donna to realize that I was in her as far as I could go; when she did, I could hear the raw, unadulterated lust in her voice as she softly said "Holy Christ, that feels good!"
A moment later, she told me "Once we got past the big part, the rest of you was pretty easy, Uncle Ted. If you wanted to start, you know, moving in me, I think it'd be okay."
With her obviously being comfortable about having my cock buried in her ass, there wasn't anything else for me to do except start moving in her. I slid myself about a quarter of the way out of her, paused for a moment, then reversed direction. She didn't voice any complaints, so I did it again, a little farther and a little faster — which she also found acceptable. No more than a couple of minutes later, I was steadily sliding nearly the entire length of my erection back and forth through the tight ring of her anus — accompanied by Donna's nearly constant sounds of pleasure and arousal.
When I looked down to where Donna and I were joined, I was transfixed by the sight of her pucker being pulled out when my manhood slid out of her, only to be pushed in when I pressed myself back in. I don't know how many times I cycled in and out of her while watching that uncommonly erotic vision.
My reverie was interrupted by the feeling of Donna's hand; it took me a second to realize that she had reached back between her legs and was busily masturbating herself as I continued to steadily piston myself in and out of her nethers. The smell of her arousal was thick in the air, telling me that she wasn't just comfortable about having my cock in her ass, but actually enjoying it. That realization got the idea into my head that there was a distinct possibility that she'd want me to fuck her that way again — and more than once. And the chance of that happening had the effect of throwing gasoline on the coals of my desire; while still being careful not to hurt her, and always alert to having her let me know if she needed or wanted me to stop, I gradually increased the tempo and "enthusiasm" of my thrusts into her. Much to my amazement, my efforts only seemed to arouse her even more.