Heathcliff Erbe

Heiss Clif Arber is an anime-only character introduced in the Bonus Episode: Yet Another Man's Battlefield. He was as an Ishvalan cadet around the same time that Roy Mustang and Maes Hughes also enlisted in the military. Heiss joined in hope of becoming an officer and eliminating discrimination from within in the military, much like the motivations of Major Miles, another Ishvalan soldier.

Due to his race, many other soldiers constantly harassed and threatened Heiss whenever running into him, usually exclaiming, "Ew, I've got the stench of an Ishvalan on me!"

Roy Mustang first met up with him during one of these encounters, and, disgusted by the fellow soldier's behavior, tried to assist him. He later got into a brawl with the same four men upon seeing the situation yet again and, with the aid of Hughes, finally set everything straight. The three young cadets formed a friendship afterwards in their early academy days, up until the Ishval Civil War.

Due to him being clad in standard Ishval attire during the war, Heiss apparently dropped out of the military upon its start, or was booted out due to his race. Either way, he met up with Roy Mustang yet again when Mustang was ordered to take out another group of Ishvalians. The reunion was a heavy one, with Mustang in awe over finding his old friend standing before him, and Heiss in shock over seeing the man who defended him all those years ago now slaughtering his people. Full of anger and hatred, Heiss suddenly fired upon Mustang with a handgun, dropping him, but Maes leapt out in that same moment, immediately retaliating by shooting Heiss in the temple, killing him. Mustang survived due to his State Alchemist watch catching the bullet, but was left in despair over the actions of the military and himself.

Trivia

 * The anime version has Mustang regretting his actions due to the murder of Heiss Clif Arber, whereas in the manga it simply starts there with no previous backstory.