This is AMAZING! I'm imaging a reformed pirate, a large man with dark eyes and a quiet demeanor. When you arrive at Zora Hall, he's there. He recognizes you. Mikau! His friend. This man abandoned his pirate crew when they stole Lulu's eggs.
Infiltrating the fortress, in a moment of silence he turns to you and Tatl. "Your heart, it beats with courage. Just like him," The man mumbles. "Tell me, then? Why are you wearing Mikau's face like a mask? Why have you taken the form of my friend?"
Tatl explains the Song of Healing, the Mask Salesman, everything. That Mikau asked us to do this. The mysterious man lowers his spear.
"...I apologize. Not to you, deceitful boy. But to Mikau, for disrespecting his final wish. Let's go."
As he walks on, Tatl asks Link, "I get he's scary and all, but why do you keep looking at that man like you've seen a ghost? He's helping with Lulu's eggs. Isn't that what we want?"
After recovering the eggs, Link stands atop the legendary sea turtle. The mysterious man stands at the edge, nodding at Link in recognition.
"Link, was it? Your courage shines over these cloudy waters like a lighthouse. Mikau would be proud to have his face paired with your brave actions. Then tell me, boy... That darkness in your eyes? That sharp look that seems reserved for me, and me alone... What did I do to deserve it?"
"...could it be I'm wearing a familiar face as well? The way you look at me, I swear you've hated me for a lifetime."
Link's eyes soften, but he does not break his gaze.
"It's good that we speak with actions, then. Faces mean nothing. Just another mask to deceive. Link, boy from another land, you have my undying gratitude. Wear Mikau's mask with honor. And I will wear this face with a heart of justice, to make up for whoever wore it before."
Link nods, and enters the Great Bay Temple.