Maes Hughes loved her, and that love destroyed him.

Gracia Hughes. This is the woman Maes Hughes loved and worshipped to the point that he could never think of laying a hand on her or any resemblance of her (much to many regret). The mother of his beloved child. It's no boast to suggest that, along with Roy, Gracia shared the responsibility in making Maes Hughes the great man he was.
With exception to Hohenheim & Trisha and Izumi & Sig, Maes and Gracia are the married FMA couple. Without the 'will they/won't they?' tension of Edward & Winry or Roy & Riza, the Hughes' relationship is written in stone. This is ironic because the series gives very little on the couple. Since the major perspective of Hughes is Elysia's Doting Daddy or Roy's Best Friend, his role as Gracia's Devoted Husband gets sidelined. When Envy makes his fatal trick on Hughes by taking on Gracia's appearance, the viewer is rather confused. Wouldn't Elysia be a better choice?
And yet, Gracia has our interest, mainly because of her relationship with Hughes. If Hughes couldn't kill a resemblance of her, even if his life depended on it, he must have loved Gracia dearly. And since Hughes is no idiot (at least when it comes to government officials, but everybody in FMA made that mistake), then Gracia must have been a special person to deserve his love. And the evidence proves it. If the Homunculus represents the evil side, and Edward, Roy, and much of the cast are of the gray side, then Gracia belongs in the good side. She represents the series' theme of family, a strong reminder to what Edward, Alphonse, and Winry once enjoyed and lost. She represents the innocence and endurance against the horrors that occur throughout the series. And for someone with a small appearance, she exists in three incarnations in the entire franchise: the Manga, Anime1, and the real-world version in the Anime1 movie Fullmetal Alchemist: Conqueror of Shamballa. All three incarnations are the same person, but each has their distinguishing traits. This writer feels it appropriate to discuss each version.

All three versions of Gracia share bobbed brown hair and green eyes. All three are loving and kind, open to hospitality for anyone regardless of familiarity or race. The most important comparison is their love for Maes Hughes. This love and loyalty is strong enough to endure some messy facts about the man. Judging by the skills of firearms and knives, all three Hughes must have experienced the ultimate crime of taking a life. Whereas this could turn off some women, all three Gracias are forgiving to each men they loved.
They also share a lack of background. We don't know where she came from. Was she an heiress that Hughes married for love? Was she a nurse who met Hughes as a patient? Was she a soldier who retired for marriage and motherhood? Did she come from a loving family or a cold, unloving one? We don't know.
Whatever her past, Gracia exists in the present. Her first appearance is in the Manga, shortly after the Lab 5 incident. Maes Hughes welcomes Winry to his home, where mother and daughter are waiting. Author Arakawa draws Gracia as a beautiful woman, with attractive eye-lashed eyes and a nice figure. She is also rather reserved in manner. She complements her husband's enthusiastic behavior to their daughter with calm bewilderment. Several times it appears she's a little embarrassed at her family's behavior (Elysia tugging at Winry, etc.). She also sounds disappointed about her husband's generous nature, in terms of it never getting its reward. Perhaps her translated name 'Glacier' gives a better clue to her personality. This doesn't mean she's cold. After all, anyone would suffer in comparison to her husband's jovial tone.
On the other hand, her calm nature serves as her strength. At Hughes' funeral, Gracia stands erect to her daughter's confusion and pleas. One gets the idea that she is the disciplinarian of the family (Can you imagine Hughes spanking his daughter? Didn't think so). This perseverance is best shown when the Brothers Elric pay their respects to the widow. Gracia refuses to blame the boys for their believed responsibility in her husband's death. In fact, she persuades them to continue their search for their bodily restoration out of respect to her husband. For all her reservations, she is proud of her late husband and wishes to see his legacy continue from the people he helped. Formerly disillusioned about their quest, considering the death it brought, Ed and Al regain their confidence. It is only after the boys depart that Gracia allows herself the weakness to weep for the man she loved and lost.

[On a side note: Riza once quoted Hughes saying "I have no right to choose my death after taking another's life." This doesn't sound like the doting daddy we all know. With that point, one wonders why Hughes wanted a child in the first place? He knows he might be tried and executed for war crimes once Roy makes it to the Fuhrership. It sounds cruel of him to create a family knowing he probably won't see the kid grow up. This leads to one conclusion: Elysia was an accident.]

The Gracia of the first Anime adaptation is much different. The Anime Studio Bones decided to add more of Hughes to the adaptation. Whereas the Brothers first meet the Lieutenant Colonel shortly after the adventure in Liore (Reole) in 1915, Anime1 has their first meeting happen four years earlier (1911) on the Brothers' first visit to Central. As a result, Gracia's appearance is also enlarged. During Edward's studies to become a State Alchemist, Hughes invites the boys and Nina Tucker to his house, introducing his six-months-pregnant wife (Bones also decided to add another year to Elsyia's life, since the Manga implies the Brothers started their journey before the girl was born). Turns out the couple have planned a birthday party for Edward! This party is interrupted by Gracia going into labor. As Hughes leaves to get the doctor, the brothers play midwives to the expectant mother. All ends happily with Elysia's birth, giving the would-be Alchemists wonder about the nature of mothers, and a good memory of their mother. It must be noted that Bones adapted Gracia's condition from a Manga story where the Brothers and Winry deal with a woman's delivery in Rush Valley. Despite this source, it is correct to consider the pregnancy situation to be part of the Anime1Gracia's history and character.
This Gracia looks different. Gone are the eyelashes, replaced by a more innocent demeanor. And yet the Anime gives a racier side to their relationship, if we are to believe Hughes' words in his first animated appearance (By different translations his comments range from his wife being 'hotter than a love goddess' to his worry that her breasts might shrink). An equally telling moment is when Gracia describes her pregnancy to Edward and Al. Hughes is blushing, his pride can either be expectant parenthood or sexual prowess.
Whereas her Manga counterpart is reserved, Anime1Gracia lets her hair down. She can get angry at her husband (when he misinterprets her declaration of 'Its coming!'). She can also be humorous. When her husband denies her going into labor, saying it's not time yet, Gracia shouts at him that it's the baby who makes the decision. She jokes to the kids that her delivery might count as a party game. Forget calm stances: this Gracia can freely shout out 'I'm dying!' much to the shock of the children around her. Given this lack, this Gracia doesn't appear bothered at all by her husband's behavior. The only worry she gives is her concern for her husband's safety. In their last scene together in Episode 25, Gracia urges Maes to be careful. She would also give this advice to Shieszka and Winry.
Other traits are noticed. Gracia possesses some knowledge about delivering babies (experience as a midwife, or a nurse?), telling Edward to get a pot of hot water. She possesses great culinary skill. She displays a huge feast for Edward's birthday (the ordeal probably causing her premature labor). Her apple pie cooking is mentioned often, as a gift to Roy in 1909 (Episode 25 flashback) and a goodbye gift to the Brothers Elric (Episode 25 present). At Elysia's 4th birthday, she tells her recipe to a guest.
Most of her scenes are of family. Photographs of her, Elysia, and Maes make appearances in episodes 7, 25, 26, and 36. In Episode 5, Gracia rubs her newborn baby's face to her cheek. In Episode 6 she interrupts her husband's time with her daughter by cradling her into her arms. Much later on, the woman gazes at her child as Elysia chalk-draws the sidewalk. She is inseparable from her daughter, keeping a happy face like her husband had done. Whereas MangaGracia's last appearance (so far) was one of tears, Anime1Gracia's is one of hope. At the cemetery she looks on proudly as Elysia talks to her father's tombstone. To her, life goes on with her daughter.

Finally, there is the Gracia of Conqueror of Shamballa. As I discussed in my Nazi Hughes…A Perspective, I noted that the real world counterparts are a lot more similar to the FMA characters than some fans have perceived. Gracia is the top example. She is as nice and kind as the Gracias of the FMA world.
The Gracia of our world is a German woman living in 1923 Bavaria. She is not married, living independently in a flower shop. A hospitable woman, she allows Edward Elric and Alphonse Heidrich room-and-board upstairs. Like her counterparts, this Gracia reminds Edward of family. He is comfortable around her, and she notices it. Does she, the woman asks, remind him of her mother? With humor, she adds if the resemblance is actually romantic. As Bavaria becomes a hotbed for power struggles and the rising Nazi Party, most of the inhabitants take it in stride and expectation. Gracia, however, is very worried about the Party's plans of a pure Germany. Except for Alphonse Heidrich, she is the only person who treats the gypsy Noah without the racism that marks the other characters (like the Maes Hughes of this world). She gives Noah clothing and allows her assistance at her flower shop.
In one Japanese translation to CoS, Gracia talks to Noah about the Nazis wanting to remove the Jews out of Germany. Interesting subject from her, since talking about the Gypsies would have been a better choice. Also, several times Jews and Gypsies are mentioned together by several people (the disfigured war veteran, for instance). Hughes mentions the Gypsies a lot, but never once does he mention Jews. Perhaps he doesn't want to offend a certain someone? These hints give the conclusion that this Gracia is Jewish, which puts an interesting twist to her relationship with the Nazi Hughes.
Although lacking her manga counterpart's attractiveness, this Gracia is pretty. She's the only Gracia to sport lipstick. And she is a strong attraction to the Hughes of this world. Nevertheless, this Gracia is not a pushover. When Hughes tries to talk to her about the Noah problem, Gracia shrugs away. In the next scene, when Hughes cruelly insults Noah, Gracia stands up to the man, leaving the guy speechless. And yet, a bond is present between the two (perhaps more visible than their more popular counterparts, at least in co-presence instead of oral recollection). Hughes loves Gracia but lacks the confidence to do so. Gracia shares similar feelings, but she is disappointed in his racism, causing her to reproach him. And yet she has faith in him, asking him to keep Noah safe.
But there is a resolution: At the end, on the morning after the Putsch, we see Gracia arranging some flowers. She turns around. She spots a man hiding in an alley. Hughes. Gracia knows, and smiles. And Hughes looks back, swallows his fears, and reveals himself. He strides to her, ready for anything. One can argue, that this is the most romantic scene of the Maes & Gracia relationship in the entire FMA multiverse (CoS critics, disappointed over the lack of certain coupling resolutions, completely ignore this resolution in their criticisms). Its evidence is reinforced by the scene of the couple standing side-by-side at Alphonse Heidrich's funeral. This Gracia tops her counterparts' conclusions by getting a happy ending with Hughes. It is probable that her influence will quell the man's prejudice and perhaps make him like his doppelgangers.
But is it really a happy ending? One remembers that the Nazi Putsch was just a setback for Adolf Hitler. Like Amestris, a Fuhrer will rise. Another Fuhrer who will also destroy this Maes and Gracia's happiness just as he destroyed millions of people. Guess that is the sad, enduring truth about the many Maes Hughes and their Gracias: Their happiness will always be brief and perhaps tragic. But it will be glorious too. In that case, allow me to quote the last line from Tenchi Muyo in Love (1996) as the perfect epitaph for Gracia and her Maes:

Time is short. But Nobuyuki and I will live our lives to the fullest, I swear. That is all that really matters.