Fohl Fayon/Relationships

Naofumi Iwatani
While Naofumi was ultimately Fohl's dear sister's savior, Fohl was ultimately antagonistic towards Naofumi. This was mainly driven by Fohl's sister-complex and Atla's repeated rampages and advances towards Naofumi. Since he saw his sister as perfect, he considered Naofumi an enemy who was trying to harm his dear sister. Anything Naofumi said towards Atla, positive or negative, was seen from the worst possible perspective. However, as Fohl slowly matured, he started cooperative with Naofumi and started seeing him in a better light.

Anime Spoiler

Raphtalia.
Fohl considers Raphtalia to be like a big sister. He respects her and does what she asks of him.

Aultcray Melromarc XXXII
After Fohl and Atla reach Melromarc for the first time, it is revealed that their mother was Aultcray's believed-dead sister. Atla is the splitting image of her sister, albeit demi-human while Fohl looks like Aultcray hated enemy Tyran (who's son married Aultcray's sister). Therefore, before Aultcray was re-awakened, he showed hatred an animosity towards Fohl.

After Aultcray was re-awakened, he treats Fohl with respect and Fohl does likewise.

Takt Alsaholn Faubrey
Anime Spoiler

Atla Fayon
Atla is Fohl's dearly beloved sister and only remaining family member. When their father and mother died, it was his responsibility to pay for the expensive medicine needed to treat her illness. They stripped everything of their mansion and eventually sold themselves as slaves to pay for it. Fohl then fought in the coliseum to pay for the medicine. During this time, Fohl started developing a sister-complex where she is perfect and that he must protect her from all harm at all costs.

When Naofumi bought Fohl and Atla, Fohl was willing to serve Naofumi eternally in order to treat Atla's illness. When her genetic disorder was cured permanently, he was shocked and overwhelmed with joy. He then reaffirmed his promise to Naofumi. However, his sister-complex got him in trouble often. Atla's advances towards Naofumi were considered Naofumi's fault and eventually, Atla became so powerful in her use in Hengen Muso that Fohl could no longer control her. For the first time, he was the useless one of the two siblings and her resolved to get stronger. Slowly, he matured and started getting over his sister-complex. He was finally convinced by Raphtalia to keep Atla's rampages under control and when it came time for the village to fight against the Phoenix, he eventually let her choose to join (after an intense battle between the two).

Anime Spoiler