Professor Nalerof had originally thought that he was working to improve the Gravity Belts keeping the Yietta metropolis afloat. However, he eventually realized that the company he was working for was a dummy and that he was in fact contributing to the efforts of a rogue military faction led by Lord Guizel. His research was being used to turn the gravity belts into what his Elysse would later term "a monstrous nightmare". Nalerof made an effort to sabotage the Gravity Diffusion Array, locking the controls with a password, but Guizel found out about his plans and sent soldiers to kill him. In a desparate effort, Nalerof took his daughter Elysse and sent her to the surface in an escape pod...just as the soldiers shot him dead.
Yuu is Ai's calm and quiet twin brother. His health is very bad and he constantly falls into illness. He loves drawing and his lifelong wish is to see magic at least once. He loves his twin sister very deeply, though it's not known if his feelings are romantic like hers or not. On his 13th birthday he falls into a serious illness and the Shadow of Death starts lurking around him, showing that he doesn't have much time left. For the sake of curing him and to grant his wish of seeing magic Ai finally decides to become a witch. However, this causes him to lose all his memories of Ai as a sacrifice to the Goddess.
Hana is a beautiful 16 girl who's trying to become a star, she's Ai's second oldest sister. She, like the rest of her family, carries the "witch sequence" in her DNA and is a Sleeping Witch, one who's powers are not awakened and can therefor not use the craft. She is usually bright and happy but often feels inferior and like she can't do anything to help her family.
Selim Bradley is the son of Führer King Bradley. In the manga and 2009 anime series, Selim is the Führer's sprightly son. He frequently asks his father to tell him stories from the battlefront and interesting anecdotes from his everyday events. Selim professes a desire to become a State Alchemist so as to be more useful to the Führer and is a self-professed fan of Edward Elric. It is later revealed that Selim is not Bradley's biological son, but rather adopted from a distant relative and, specifically in Brotherhood, he is revealed as the Homunculus known as Pride. Pride is the first Homunculus that Father created. He is the most powerful of the Homunculi and seemingly the highest ranked, as he is seen giving orders to Sloth and Envy. Thus, he is generally respected by the others. He is extremely cruel, heartlessly ruthless and extremely devoted to Father's cause. He refers to his enemies as "mister (plus a nickname)" in mocking respect and often makes big smiles and casual talks before attacking. He has also proven himself to be quite clever and resourceful. His attacks mainly center around manipulating shadows, which is convenient, because it's virtually impossible to eliminate one's shadow. (Source: FMA Wikia)