Fi tells Link that his body is what's causing the erection.

All of a sudden, Fi couldn't seem to meet Link's eyes. In fact, she was blushing a little. She told Link that Peatrice was not the one who have her the erection, but Link. Her own body was turning her one greatly.

That completely flabbergasted Link for a few moments, before sighing. He told her that he did, in fact, find her very attractive physically, but her lack of emotional attachment to anything made him focus on other things. Still, this erection needed to be dealt with. Link told Fi that when Peatrice came back, she would need to tell Peatrice something.

Sure enough, a few minutes later Peatrice reentered the room to find her boyfriend and his sword spirit waiting for her. Fi immediately told Peatrice that something had come up, and they needed to go.

Before she could ask them questions, Link said in a robotic tone of voice, "The Sealed Temple is under attack by a great evil. My Master needs to leave, immediately."

The sad, lonely look that Peatrice let slip for just a moment at the news made both Link and Fi's hearts fall, but she ended up smiling. "I understand. After all, you're a hero, honey. Go get em!" They rose to leave, but before they did, to Link's surprise, Fi walked over to Peatrice and kissed her on the lips, passionately. Then they both left, leaving Peatrice standing there, her face red.

A little bit of flying later, and the two were on an uninhabited island some ways away from Skyloft, in a secluded cave. Much to Link's annoyance, Fi's erection had not dissipated in the slightest. Rolling his eyes, and then realizing that with Fi's body that accomplished nothing at all without pupils, Link turned around and bent over, displaying his large, blue tush for Fi. "This is probably what excited me the most about your body, Master," Link said, wanting to get this over with. "In order to relieve yourself, you must disrobe your lower half..." before he'd even finished speaking, Fi had taken off her pants and undergarments, her eyes never leaving Link's bottom. "...then grasp your cock," he continued, putting gentle, sensual emphasis on the word. Fi did so immediately, moaning lowly once contact was made. "Then you stroke it, stroke it while thinking of me."