We know Lucia and Livia are sisters. We know that Lucia was a Garlean spy when she first came to Ishgard. We know Gaius took them in (or at least, Livia in) when their parents were killed. Livia takes to their new foster father rather too quickly. Lucia has her doubts, and her relationship with her sister is becoming increasingly strained as a result.

Gaius wants to bring Lucia into the fold.

Livia has her own ideas about what that means.

Lucia wants her family back, but this isn’t her family.