She just turned 18! (I gave her a headcanon birthday.) But she was also sealed away for like ~40 years before coming here, so she's technically a spry 58-ish years old.

Zelda also loves being science buddies with Luca! She thinks he's brilliant (memory issues aside) and she feels like she's learning a lot from him. I would love for Luca to help her build her little robot later on! She was only like 5 or 6 when she built it with her mother originally and she might not receive any schematics for it from the wishing well.