Brigitta Lycaon, Grand Trad's igniter merchant, will speak to you once you reach the capital. Her bond grants you access to the Merchant, one of the most unique Archetypes in Metaphor ReFantazio. Getting the right answers with her will earn you some magla to spend on researching this lineage.

You'll need Wisdom rank two to unlock Brigitta. She'll then give you the A Bullish Embargo quest to defeat a monster in Belega Corridor, which isn't too difficult. Finish the quest to unlock Brigitta's bond (or Social Link, if you're used to Persona terms) and unlock the Merchant Archetype.

Here are the answers we used to level up Brigitta's social link in Metaphor ReFantazio.

To get Brigitta's bond to level five, you need level three Courage. To reach level seven with her, you need level four Courage.