(Note: As an idiot as I am, I thought I add a bit of a twist to this.)
The dragon raises an eyebrow as you approach its rear foot. With a slow, heavy crunch, it sits down, lifting one rear claw for you to examine closely. The massive limb is taller than you are. It is vaguely reptilian, with three long toes on the top, and one shorter, more thumblike claw near the heel. Each of them is tipped by a jagged obsidian-like claw the size of a greatsword. While the top of the creature's foot is covered in hard blue scales, each of them as large as a buckler, the underside is softer and smooth, and its color is a light yellowish cream.
You move closer, reaching out to touch the flesh. It is soft and slightly ridged, compressing under your touch like a heavy mattress. This close, the scent of the sweaty unwashed dragon flesh is overpowering. Beads of glistening sweat clean to the soft sole of the foot, and they smell enticing and powerful. Touching one marble-sized bead, it sticks to your skin like slime, thick and viscous. You raise it to your nose, breathing deeply.
The scent is unlike anything else you have smelled before. Something about it is dirty and primal, and it is unmistakably sweat. It carries a heavy undertone of filthy, hot gym lockers that should be disgusting. But layered on top is a soporific incense-like scent, reminiscent of the smell of an extinguished candle. At the back of your nose, there is a final sharp scent of exotic spices, all of it combining to create a musk that you would roll around in if you could.
The dragon wiggles his toes slightly as you touch his foot, clearly a little ticklish. You press your hands against the flesh, feeling it gently. It is soft at first, but beneath you can feel the hard, hot form of powerful muscle. The flesh is exuding heat like a radiator, and it makes you sweat so close to it.
The dragon is grinning, clearly enjoying your interest.
"Do you like what you see, human?"
Gritting your teeth, ashamed of your arousal, you nod, which makes him laugh wickedly.
"Ah, you wish to partake of a taste of my strong, sweaty paws? Very well, you shall have a lifetime of them."
The dragon stands over you, his huge, warm body casting a shadow over the cave, and slowly lowers his back foot onto you, pressing you down onto the floor. You lie on your belly as he presses his foot onto your back, the damp, sweaty skin covering you as he pushes down harder and harder. The strong, musky scent of his foot stings your nose, and you groan at the pressure, your cock becoming hard, stretching and oozing until finally, you cum furiously over the floor and the dragon forces his foot to the ground with a sudden crunch.
After a moment, you slowly open your eyes and groan, and put your hand over your head, wondering what happened and soon felt something weird on top of your head. Most of all, your body feels weird, like it's connected to something. Big and strong, but oddly strange like most of your body that is connected to something isn't moving. What's that in front of your face, obscuring your lower vision? Also, you smell something weird, awful, and something that smells like a stinky foot and you make a muffled groan as you shake your head and you can also taste it too, gross. It seems like you're stuffed with something of this odd smell.
You try to gain your full sense of what happened. You were wondering in a cave, that is actually a dragon's den, it asks you a strange question to save you from being eaten. You chose to be his foot... "Oh no.." You think to yourself and a voice replies to your despair, "Oh yes..." You then notice how odd your body feels right now. You can feel and hear a muffled sound of a heartbeat that doesn't sound human as it pumps and throbs in your bizarre body. Your neck feels heavy and thick as you try to look up and down and see the belly to forelimb of a dragon in front of you. "This isn't happening..." You mentally say as you turn your head to your right as far as you can and wiggle your right arm up and down, only to find your right arm is the dragon's right toe. And then turn to your left and did the same. The left toe moved under your control. You hope this is a dream, but it isn't as you let out a muffled scream physically even though you have no mouth or lungs to speak of. Probably the dragon's magic to let you have it just for his entertainment as he hear his victim (you) and mentally scream as well as you hear a dragon's laughter as it rumbles above you.
He then raises you up from eye level level as your you feel your new limbs weigh down but you struggle to look up at his face. He can't see your horror but he knows you're in his foot and feel his breath as he speaks, "Well, how do you like being a foot, human?" you let out a muffled whimper as you curl your toes inward to your/his foot, scared as you still hope it's just a bad dream. "Sorry human, but this is as real as it can be!" the dragon lets out a chuckle and continues, "You know, I'll let you keep your useless mind so you can remember who you once were and what you are now and forever, and as a bonus, I think you'll have your own and also useless will to move on your own, but most of the time, I'll be manipulating your/my foot and toes as we walk! And to make you feel nice at your new place permanently, I'll give you a nice warming welcome as my foot!"
He then moves your/his foot close to his face as he curls up to you, he then gives you a massage from his tongue as you twitch your/his foot and toes and moan as your fear and shock is immediately gone as you let out a nice pleasurable groan as your relax and let him lick your foot body and lift whatever toe he's going to lick just to help him out a little. If you want more of those foot licking, you better be a good living foot slave for him.
He then puts you back down on the ground as he looks down and asks you and so you remember where your places is, "You do know where you're going to be at now and forever, right?" You let a little muffled whimper and move your middle toe (your head) up and down and nod and mentally told him, "Yes master." He chuckled, "Good!"
He then curls up close to you as he then falls asleep and you feel his breath and you twitch as you don't need to sleep for some strange reason. "I need to find you another partner for my other foot, you must feel lonely without a foot partner?" you then nod again as he then falls asleep and you just watch. His powers holding your mind together so you can entertain him with your useless moans and movements.
The next day...