I have come back for more—
Collaring(even though it really isnt a kink because it's a symbolization of a relationship but I'm just curious!) and Sensory Deprivation
Like you said, it's not so much a kink, but more so a symbol of a relationship. A possessive mark.
If it isn't enough for people to understand that I've laid claim to your body through the scratches on your back and numerous hickies I've left up and down your neck... the bite marks on your ass... the purple bruises left on your hips and the base of your spine... A nice, pretty collar of your choice might send the message.
I'll get you two- one in your favorite color, for the daytime, when you're out and about, showing that gorgeous neck off, with a little shiny "Touya" engraved pendant glimmering in the sun. And another one in my favorite color, to wear at home. When you're walking around me, doing your daily mundane tasks, your collar dangling around your throat, making me smile at the physical proof of our obsessive commitment.
Also allows easy access for me to leash you up, take control, and pull you around to my whims. I might take you on a nice, leisurely stroll to our bedroom, where we have some fun and I leave some more angry marks on and around your neck.