Gatrie

Fire Emblem: Path of Radiance
Gatrie originally joins Ike's party in Chapter 5, alongside his fried Shinon. But, at the start of Chapter 8, they leave due to their lack of confidince in their new leader. He returns as an ally in Chapter 13, but can only rejoin the main party permanently if Astrid, who is also recruitable in that chapter, has a conversation with him.