The two of you met how many of these stories go. Just a lost human wander through the wilderness. Finding a cave, his nest. And sheltering for the night. A lone harpy enters, eyeing you up in a defective manner. You offer what little food you had to stay and they begrudgingly agrees. That where it started.
When you found your way back to civilization, you find yourself making the trech back. At first just for observation, you don't usually see harpy this close after all. As you continued, the two of you grew closer. To the point when you offered food they dove straight for you, pecking you cheek and other sorts of birdly love.
Now you found your in his nest, seeing him soaring through the sky. You have a singular thought, one that you can't seem to shake. "What if I could do that?" Now you've built crossbows and other machical gizmos. But a pair of wings? You couldn't do that, right? Or could you.
You sketch a prototype, actually a few. Mainly based off their wings. And you build it, your prototype. It doesn't work first try, but nothing does. But with every fail you refine it. Till it works, and works rather well.
You stand and look at your lovers nest. This is the day. You climb, your prototype on you back. In their nest you find them gnawing on something as you enter. Their attention immediately turns to you, then to the contraption on your back.
You extended a hand pointing out the cave "Fly?"
"Fly?" They repeat unsure of what you mean.
You take a few steps back and get a running start as you jump out of the cave. "FLY!" You yell with laughter as your wings unfurl.
Their look turn to horror to amazement as they watch you glide out of the nest. They catch up with you, chirping and laughing as they see their human glide.
They move closer to you, placing their hand in yours. The two of you enjoy this moment as you both slowly descend.
You both reach the ground, and safe and sound. They turn to you and holds you up, arms shaking as they do so. He spin both of you around, repeating "human flew, human flew!"
He set you down and pulls you into a large hug, their wings encasing you. They pull away, claws on you cheeks. "You fly." They say grinning ear to ear, full of excitement.
"Yes, yes I did."