Initially, when my husband would call me by a specific name- well it changed with time, but when the name came up, it meant he wanted me to submit. (For the curious, I was his pet, to begin with. I'm sure you can all imagine subsequent names.)
It also wasn't viable for us to be completely in those roles at all times. We're still trying to navigate that, as we both have limitations that require constant adjustment- if I'm particularly depressed, or he's in a lot of pain, we're not going to be able to share that dynamic as much. Then again, I think... well, I could probably use my own thread to discuss that stuff. Maybe I will...