ok... here goes...
In FE7, Zephiel was sorely abused by his father. Though he tried his best, his father still hated him. Now, after Eliwood defeated the dragon, peace returned. However, Bern and Etruria had come out in a war. During a battle, the King of Bern (Desmond) tried to assasinate the teenage Zephiel. However, since Zehphiel was skilled at combat, he accidentally killed his father. With that, he became insane. Then, when he had returned to Bern, Zephiel's supporters crowned him king. With the knowledge of Hartmut's secret libraries, he managed to ressurect a demon dragon. Yan (enigmatic man) approaches him and asks him why. When Zephiel explains, Yan reveals his true form (mamkute-dragon). With that, Zephiel unleshes an onslught of dragons. With the help of Fa's demonized sister, Idoun, he raided Etruria. Then, since Lycia is Etruria's ally, Ostia offered to help. Roy was studying inOstia when the castle was raided. Thanks to Pherae's armies, Roy learns that Hector was captured. Roy then rushes to Hector's side of battle but found him dying. When he talks to him, Hector tells him to take care of his daughter, Lilina (ironically, he never wanted Roy to take Lilina before). Hector then dies... (I don't need to spoil more)