When Fyrian is only successful at returning to the swamp by yelling for Luna, it makes it very clear that Xan’s magic is already flowing into Luna and making her far more powerful than Xan. However, it’s also worth noting that Fyrian had the wherewithal to think of calling for Luna in the first place. This speaks to the strength of their bond as family members, while the fact that Luna’s name brought him home suggests that within the logic of the novel, family will always be there to help each other.