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.

Relationships
Scar - May stumbles across Scar during her travels in Amestris and seems to immediately like him, despite his gruff personality and his initial obsession with revenge and murder. May is the first one in the story to treat Scar as a person rather than as an opponent.

Alphonse Elric - May first had a crush on the Fullmetal Alchemist, but once she met Edward, his short stature and shorter temper put the two immediately at odds with each other; May's romantic dream was shattered. Later, while recovering from injuries at Dr. Knox's house with Alphonse, she asks Al if his real body resembles Edward. Alphonse, outraged (or as outraged as Al can be) insists rather defensively that he is taller, handsomer, and more polite than his elder brother, and May immediately transfers her affections to the younger Elric, imagining him to be a dashing knight in shining armor. For the rest of the story she refers to him as "Alphonse-sama" and although they bicker while she tries to teach him Alkahestry in the North, due to their mutual intelligence and combat skills they work well together in several adventures, including cracking Scar's brother's code and capturing Envy. May weeps when they part ways. Reunited during the final battle with Father, Alphonse goes to great lengths to protect May and then asks her to help him make a terrible sacrifice, to which she reluctantly agrees. Her relief at seeing Alphonse return in his former body brings her to near-hysteric tears. Two years later, Alphonse departs for Xing to visit May and learn Alkahestry from her. The two appear later in the new Elric family photo, suggesting they have become romantically involved.

Lan Fan and Ling Yao - Ling is May's older half-brother, but Lan Fan is the only other Xingese person with whom May has an extended conversation during the story. Because they come from rival clans, upon seeing each other both May and Lan Fan immediately tried to kill each other, despite the fact that both were injured and currently recovering under Dr. Knox's care. Knox immediately defused their stand-off, and his description of the Ishval Massacre caused the girls to lose the will to fight. Much later, after the last fight with Father, May despairs that Ling, having been a Homunculus, has won the race to bring the secret of immortality to the Emperor of Xing. However, Lan Fan asks Ling to protect the Chang clan when he becomes Emperor, to which Ling readily agrees, much to May's surprise.

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. She later asks him if his real body is similar to Edward's and Alphonse reacts as if May had insulted him; he becomes rather defensive and insists to May that he is taller, handsomer, and more polite than his older brother. May, envisioning Alphonse as a dashing prince, finds herself crushing on the younger Elric 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.

North to Briggs
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).

Back to Xing?
However, as May passes through an eastern Amestrian town bordering the desert, their kindness guilts her into remaining in Amestris to help the country fight against the homunculus. Envy encourages May to return to Father's lair, and May heads off to Central.

It's unclear what May did during the time skip, but presumably part of it was spent traveling from Briggs to the eastern town, and then from the town back to Central. When next we see her she has just arrived in Central and is heading through the same tunnels to Father's lair that she traversed with Scar earlier in the series when she, Envy and Xiao May encounter a horde of Mannequin Soldier Homunculi. May fights them off but Envy manages to absorb most of the soldiers and returns to his former form. A fight then ensues, and from Envy's reaction May determines the correct direction to Father's lair. The two of them fight in the pipelines beneath the city and finally fall through to the chamber below Laboratory 3, where Roy, Riza, Edward, Scar, Zampano, Jerso and Darius were fighting more Mannequin soldiers. Scar, shocked to see May still in Amestris, yells at her for not returning to her country. May, shocked and confused, tears up, to which scar gruffly responds "Whatever. Don't cry." Roy and Riza stay behind to fight Envy while May and the rest of the group continue through the chamber door, and May uses her Alkahestry senses to lead them to Father's lair. However, Scar and Edward soon return to stop Roy, leaving May with the chimaera.

Later, when the Gold-Toothed Doctor and his henchmen slit Riza's throat to force Roy to perform human transmutation, May and the Chimaera pop out of the pipes in the ceiling in time to stop the Doctor's plans. The battle between Scar, the chimaera, and the henchmen resumes, and while Roy cradles Riza--who has now fainted from blood loss--May tries to retrieve the Philosopher's Stone that the Gold-Toothed Doctor dropped. However, Roy's panicked cries appeal to May's selfless nature once again; she rushes to their side and uses Alkahestry to seal Riza's wound. After urging Riza to rest, as May only stopped the bleeding and could not create more blood to replace that which she had lost, May mentions that she can once again sense enormous amounts of twisted ch'i beneath them, which causes the Gold-Toothed Doctor to panic and tell them to stay away from that place. Then a wounded Wrath arrives, followed by Pride, who absorbs the Gold-toothed Doctor and forces Roy to perform Human Transmutation, thereby transporting him to Father's den. Wrath tries to stall May, Scar, Hawkeye and the chimaera by provoking them, but, from the Gold-Toothed Doctor's earlier reaction to May's sensing the chi'i, they realize Wrath is trying to stall them. Scar stays to fight Wrath while May descends to Father's lair.

May is initially distraught to see Alphonse unconscious again, but after he reawakens and she realizes that Father has the ultimate secret to immortality (which she still seeks for the Xing Emperor) May insists she can take Father on herself with Alkahestry. Father glares at May and tells her "You don't belong here," but she tells the Elrics to take down Pride, and then attacks Father, managing to pin his arms down. She then leaps at Father to finish him despite Hohenheim's warning, but because Father can absorb her throwing knives and transmute without moving, he repels her using his Philosopher's Stones. May is knocked away, bleeding from her eyes and mouth.

Alphonse rushes to May while she partially cures herself, leaving Edward with Pride, and Alphonse protects her from Father's attack, but the Elrics' and Izumi's efforts to stop them prove futile, and Father activates the nation-wide transmutation circle, thereby opening the world's gate. May, Greed, Roy, Riza, 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. Edward is blown back by another of Father's explosions, and his automail arm is destroyed while his remaining human arm is impaled on a spike, rendering him trapped and unable to use alchemy. Alphonse, in a panic, tries to rise, but nearly cracks his blood seal. He then begs May to help him trade his soul back for Edward's arm, saying she's the only one he could ask. She 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.