During the story of Fullmetal Alchemist: Brotherhood, Edward Elric and his brother Alphonse Elric meet all kinds of new allies and enemies alike, and their ultimate nemesis is Father, who lurks underneath Central City. Father has seven homunculus villains at his disposal, from the bloodthristy Wrath to the shapeshifting Envy.
What is Envy's role? He often uses his shapeshifting to spy on humans or sabotage them, and Envy sneers at these supposedly inferior humans. He has crossed paths with the Elric brothers more than once, and sometimes, he knew just what he was doing. Other times, though, he was making a big mistake.
10 Was Right: Sparking The Civil War
This is a gruesome case where "being right" and being righteous are two different things. No one woul ever applaud Envy for what he did here, but it was the correct thing to do for Father's plans. And thousands of people paid the price.
Father wanted a bloodbath, and he got it when Envy assumed the form of an Amestris soldier and shot an Ishvalan child unprovoked, setting off the Ishval Civil War. Envy sure knows how to make history, in all the worst ways.
9 Was Wrong: Scorning Humans
For the longest time, Envy was happy to look down on humanity and scorn its many faults and shortcomings, such as the short lifespans of humans or how foolish humans can often be. He almost seemed to rival his big brother, Pride, in his arrogance.
But he was really just hiding his envy of how much humanity can learn, grow and have hope, and Envy was scorning them out of spite, not for genuine reasons. He kept up this paradigm for far too long, and he paid for it later.
8 Was Right: Protecting Father's Secrets
Early in the series, Edward and Alphonse snuck into Laboratory #5 to look into the Philosopher's Stone and see if they could obtain one somehow, or at least learn more. Edward ran into two criminal brothers who inhabited the same suit of armor, Alphonse style.
Edward defeated the brothers, and the brothers were ready to share vital information with Ed. Just in time, Envy and his companion, Lust, came along and silenced the brothers with deadly force to protect Father's schemes.
7 Was Wrong: Challenging Ed's Group Up North
Later in the story, Envy followed Edward and Scar up north, near the fortress of Briggs. He felt that he could challenge May Chang, Scar, Dr. Marcoh and the rest single-handedly, but he was proven wrong. May had created alkahestry circles under the snow, and set them off whenver Envy came close.
Envy morphed into his giant true form and seized Dr. Marcoh, but that was the wrong call. Up close, Dr. Marcoh had the chance to remove his mitten and reveal his transmutation circle. He used it to dissolve Envy's giant form and reduce that homunculus to his tiny, helpless true form.
6 Was Right: Luring May To Central
Although Envy was reduced to his tiny form, he was not quite so helpless after all. He was placed in a glass jar, and May Chang wanted to take him back to Xing to study him. But along the way, Envy talked May into turning around and heading to Central to find more Philosopher's Stones.
Just as Envy hoped, May was easily manipulated with the promise of those Stones, and during the Promised Day, Envy broke free of his jar and absorbed enough mannequin cyclops soldiers (and their Philosopher's Stones) to regain his body.
5 Was Wrong: Letting Dr. Marcoh Escape
At some point, Lust the assassin homunculus captured Dr. Marcoh and brought him back to Father, and Dr. Marcoh was put in a prison cell of sorts. Envy was tasked with guarding him, but he failed in that task.
Scar, the wrathful monk, visited and rescued Dr. Marcoh without Envy even noticing, and Scar even reshaped and destroyed a chimera to fake Dr. Marcoh's death. When Envy saw that scene, he got the wrong idea, and worse yet (for him), he had let Dr. Marcoh get away. His vigilance was lacking.
4 Was Right: Lending Ed His Stone
At some point, Gluttony the all-consuming homunculus "ate" Edward, prince Ling and Envy all at once, and transported them to an infinite stomach dimension. They seemed to be stuck there, but then Ed pieced together some Xerxes ruins and built a human transmutation circle.
This could open the Portal of Truth, but Ed needed power. Envy smartly lent Ed a portion of his own Philosopher's Stone to fuel Ed's alchemy, and pointed out that those people in the stone were already dead. Ed should not feel guilty about using them, so Ed finished the job.
3 Was Wrong: Challenging Roy's Group
Envy is a skilled assasssin and saboteur, but he struggles when he challenges the main characters of Fullmetal Alchemist in proper combat. During the Promised Day, Envy confronted Colonel Roy Mustang, Edward, Scar and others, all by himself.
Roy took charge of the situation and repeatedly blasted Envy's eyes, tongue and body, rapidly wearing down Envy's Philosopher's Stone the entire time. Envy was in agony, and he could barely even escape, let alone retaliate.
2 Was Right: Trusting Humanity
At the end of the series, Envy was defeated once again, and he finally admitted that he was envious of humanity's joys and triumphs. He had tried to pit the humans against each other and blind them with hate, but by now, trust had triumphed over hate.
Envy decided to give Ed, Scar, Roy and the others a chance to prove their worthiness, and decided to not get in their way anymore. Humanity would succeed or fail on its own merits, and Envy destroyed himself so he couldn't interfere with that.
1 Was Wrong: Falling For Riza Hawkeye's Trick
This was a cool trick that took place during Envy's desperate battle against Roy Mustang. At some point, Envy retreated into a maze of tunnels and passageways, and Roy ran in to chase him. Lieutenant Riza Hawkeye went in there too, to watch Roy's back.
Envy took on Roy's form, and Riza held him at gunpoint. Envy tried to pass himself off as Roy, but then Riza told him "the Colonel calls me Riza when we're alone," while Envy had called her by her rank. What Riza said wasn't actually true, but it didn't have to be; Envy just had to believe it. He did, and he gave up his disguise.