First a disclaimer, I'm on the spectrum so apologies if I seem like I'm attempting to rationalize things way too much. Understanding something as much as possible makes it much easier for me to accept and embrace it, and that's what I'm trying to do here.

I'd also like to make it clear that I'm not asking from a place of judgment, I'm genuinely from the bottom of my heart trying to understand, for reasons I'm about to explain.

I've been with my boyfriend a year. For the past 6 months we've had a casual dom/sub thing going. I say casual because it's not something either of us identify very strongly with or take very seriously (no offense to those who do!), but a big part of our relationship involves some light rules, rewards, and him acting very caretaker like towards me. Neither of us had any experience with this when we started, it happened naturally due to how we interact with each other and upon further research we realized we basically fell into a light BDSM dynamic without even realizing it.

He really likes being called Daddy, and he calls me his little girl, little one, or sometimes pet. There's no actual age play (I believe that's what it's called, sorry if I'm using the wrong terminology) but it's a term that fits us and how we are together. It's really grown on me and I've come to enjoy saying it, although I do get shy sometimes.

Recently while having sex he was encouraging me to say it a lot and in that moment, observing his reactions, I realized just how much it turns him on. Afterwards I asked him about it and he said yes he really really likes it but he doesn't know why. He just likes it, it makes him feel good, it's just hot.

I understand why he likes it in day to day scenarios. The way he acts with me is like a caregiver, reminiscent of a father, and I see how the term Daddy fits that. It also has a certain weight to it that feels particularly special and intimate.

As for sexual scenarios, I'm less sure. I don't mind saying it during sex and like it too, but I can't wrap my head around why. When you really think about it it does seem weird to use a term associated with fatherhood in a sexual context, especially because he has a daughter. I don't think there's anything actually incestuous meant by it though, and I guarantee he doesn't associate me with his actual child (who is an adult by the way).

So what exactly makes the term Daddy (or Mommy, or little girl, etc) sexually arousing? Is it the taboo, the implied power dynamic? Not sure about that in our case because our dynamic is very gentle and less about power differences (I think he enjoys taking care of me far more than he enjoys the power over me, in fact he's learned he's a switch and sometimes likes to be dominated in the bedroom - while still being called Daddy!). Maybe it is an incestuous fantasy for some people. Or maybe there's no reason for it, sometimes people just like what they like.

So my question for this community, what do you find sexually arousing about being called Daddy or Mommy? What do you find sexually arousing about calling your partner little girl/boy or little one? I reiterate, I'm not asking from a place of judgment. Since my boyfriend isn't sure what he likes about it I'm curious what others do.