Mei Chang

May Chang is the seventeenth royal princess of Xing, born to the Xingese Emperor and the royal concubine representing the Chang house. Though young, May has been tasked with finding a way to raise the social standing of the poor, downtrodden Chang clan in the eyes of the Emperor and has embarked on a journey to discover and present her father with the secret to immortality. Skilled as she is in the art of Xingese Alchemy, May sets out across the desert toward Amestris with her beloved pet Xiao-Mei so that she may learn about the Philosopher's Stone.

History
After a grueling and perilous trek, May finally arrives in the Amestrian frontier town of Youswell, where she uses her abilities to rescue Halling from a collapsed mine. When the residents of Youswell compare her to the first alchemist to perform an act of heroism in their town, May falls immediately in love with her misguided perception of Edward Elric (having misinterpreted Halling's description of Fullmetal and his legendary exploits) and sets off in search of him, hoping that her new imaginary lover may be able to help her strengthen her clan. She and Xiao-Mei make their way to Central (along the way just missing Edward in Resembool), where they encounter Yoki and Scar and join up with them after hearing that Scar, too, is chasing after the Fullmetal Alchemist. May is the first to recognize the symbols tattooed on Scar's right arm as the Dragon's Pulse, a purification array that represents the basis of Alkahestry.

Drawn to Scar's underlying good nature, May becomes his ally and friend, rescuing him and healing his wounds after his ill-fated encounter with the Elrics, Hawkeye and Gluttony. In return, Scar warms up to her and helps her locate and follow Alphonse Elric when it appears that he has abducted Xiao-Mei. The two follow Al and Gluttony into Father's underground lair, battling both his army of guard chimeras and the sinking feeling that the power that flows within Central is not a wholesome one.

Upon breaking into Father's inner sanctum, May learns that Edward Elric is not, in reality, the statuesque, princely figure she had fabricated and in a rage of misplaced vindication, bursts into attack, revealing that she is still able to transmute within Father's presence as Amestrian Alchemists are not. She is injured battling Gluttony and is forced to escape from the battlefield hidden inside Alphonse's armor.

Alphonse takes May to be treated at the home of Dr. Knox, where she encounters and recognizes Lan Fan as a retainer of the Yao clan and challenges her to a duel, as each of the twenty royal heirs are seeking to eliminate each other in the bid for the Emperor's favor and, subsequently, the throne. Their skirmish is cut short by the intervention of Dr. Knox, who refuses to allow two of his patients to injure each other further. As Knox tells Alphonse the gruesome story of the Ishval Civil War, May and Lan Fan listen on. May finds a kindred spirit in Alphonse and, after questioning him about his real body and the dissimilarities to his brother, finds herself crushing on Al instead.

After leaving Knox's home fully recovered, May rejoins Scar and Yoki - who now have Tim Marcoh in tow. May recognizes the name from Knox's stories of Ishval and is excited to finally have a lead to the Philosopher's Stone, but Scar tells her that she must not lust for such an evil thing. After Scar destroys the outer layer of Marcoh's face, he asks May to use Alkahestry to staunch the bleeding while leaving the wound itself intact so as to let the doctor's face heal misshapenly, disguising him from enemies.

Now that they have an Amestrian Alchemist, a Xingese Alchemist and an Ishvalan Alchemist, the group makes their next move - recovering Scar's brother's alchemy notes from the place they are hidden: Briggs. May and Marcoh head north together by train while Scar plays decoy with Yoki on foot. they find the notes, but are unable to decipher them without Scar around. May discusses the differences between Alchemy and Alkahestry, but mentions to Marcoh that his assertions regarding the origin of alchemical energy are incorrect - rather than stemming from the movement of tectonic plates in the Earth's crust, she believes that the true source of the energy is from the movement of a multitude of human souls. She also reveals she no longer wishes to use the Philosopher's Stone. Like the Elric brothers, she believes it would be wrong to use human lives and even if she just tells him how to make it, she knows he will can gather the necessary sources to do so.

After heading North, May and Tim Marcoh sneak away from the train station in disguise, as they had found out that Kimblee was pursuing them, and had the train station closely watched. Instead, Scar and Yoki (dressed up as Marcoh) confronted the Red Lotus Alchemist, and as a result Scar had critically injured him.

Afterwards, the team meets back up at the house where Scar had hidden his brother's notes. However, Scar noticed that the Briggs team was closing in, and so they had moved into an abandoned mining town to hide in. After they escape the pursuing Kimblee yet again, the group hides in the outskirts of a town where Marcoh takes on a job as a Doctor. Soon after though, Envy, who was deliberately led to the hideout, had attacked. However, the group had set traps to destroy Envy. May had placed a lot of transmutation circles on the ground before the battle, then as Envy stood on one, she would activate it using Alkahestry to injure Envy. After Envy is defeated by Tim Marcoh, who had destroyed his Philosopher's stone, May is told by Scar to return to Xing with Envy (in his original form, a small lizard).

Unfortunately, Envy manages to trick her into going to Father's den, where he escapes her grasp and successfully absorbs a lot of Mannequin Soldier Homunculi, returning to his former glory. A fight then ensues, and May finally flees to the safety of Ed and Al's group.

After Envy's defeat, and Wrath's injury, Roy is teleported to Father's den along with Pride, where Roy goes blind and Pride loses his regenerating powers. However, the toad Chimera sensed Father's den below them, and so Scar, using his destruction powers, blew a hole to Father's den, which May descends into. She then commences a battle with Father, but is at a loss, as her throwing knives are absorbed into him, and close combat moves can be stopped with Father's electric shield. After being injured, the girl partially cures herself and Alphonse protects her from Father's attack, but nobody can stop the monster, who activates the nation-wide transmutation circle. As Father succeeds in containing God within himself as well as all the citizens within Amestris, May, Greed, Roy, Izumi, Hohenheim, Alphonse, and Edward are the only ones left alive and bear witness Father's new form, much to their shock. As Father unleashes his alchemical attacks on the group, Hohenheim creates an energy shield while May literally holds the ground, preventing Father from attacking from below. After Hohenheim's failsafe activates, May continues to defend the group from Father's attacks.

Final Battle
After Father escaped to replenish his stone supply, May pursues him with Alphonse, and both are eventually struck by a beam of pure energy. The younger Elric shields her and Xiao-Mei from the full force of the attack, and falls apart in the process. Alphonse then convinces May to make a circle to restore Edward's arm at the price of Al's soul, to which the girl tearfully complies.

At the end of the battle, May is seen crying next to Al's broken armor. She happily greets him once Edward sacrifices his ability to use alchemy in order to resurrect Alphonse. Later, Ling takes her back to Xing, promising to gather all clans and protect them once he becomes the Emperor. May notes angrily that Greed has rubbed off on him.

After a two-year time skip, Alphonse prepares to travel to Xing in order to study Alkahestry with May. In the epilogue, they are seen in the new Elric family picture, suggesting that she and Alphonse are romantically involved.

Trivia

 * Mei means "beautiful" in Chinese. Also, Mei Mei means "little sister", a reference to her relation to Ling Yao. Chang is a typical Chinese surname.
 * Her English voice actress, Monica Rial, also played Lyra in the 2003 anime series.