Scar hails from the region of Ishval whose people were almost exterminated in a previous civil war against the state military, most notably their alchemists.

As the series continues, Scar's backstory is further explored and he questions his motives, eventually joining the side of the Amestrian State military, assisting in an armed coup against the government in order to defeat the organization secretly responsible for the Ishvalan Civil War.

[5] Scar is introduced in the series as a serial killer who targets alchemists working for the state military from the country of Amestris in revenge for their involvement in the Ishvalan civil war, which caused the death of several of his comrades.

[7] When Scar awakens after the incident and discovers his brother's arm attached to his own, he kills the doctors treating him, Winry Rockbell's parents, in a blind rage.

[6] Retreating from them,[9] Scar then joins with the former military lieutenant Yoki and a young immigrant named May Chang to go to Central City to continue his revenge.

[12] As he escapes, he finds Dr. Tim Marcoh, a state alchemist who participated in the Ishbalan war, who asks Scar to kill him as he is being used by the homunculi.

[16] After succeeding in their escape, Scar joins forces with the Ishbalans as well as Edward's group in order to strike on the corrupted State Military controlled by the homunculi.

[18] After defeating him, a severely wounded Scar uses the last of his strength to activate the transmutation circle that the Ishbalans secretly made around the city to enhance the alchemists' powers thanks to his brother's notes and stop the homunculi's leader.

Additionally, his backstory is largely the same as in the manga, except Roy Mustang executed Winry Rockbell's parents on military orders during the war and Scar's brother was romantically involved with his fiancé who later died of an illness.

After the sudden attack and outbreak of war, his brother came back, knowing how to create a Philosopher's Stone, but the faithful Ishbalans ignored him, and he later renounced his research.

[31] Todd Douglass Jr. from the same site called him "a deep character with a tragic past" as despite being a murderer, he comes to share the same points of view from the Elric brothers across the series.

[32] Holly Ellingwood from Active Anime noted Scar to be "a character so much deeper than just a foil for the brothers" [Edward and Alphonse Elric] due to how along the series it is shown his backstory and it is explained why is he determined to kill all the State Alchemists unlike other villains.

[33] Mania Entertainment's Chris Beveridge celebrated Scar's introduction in the second anime series Fullmetal Alchemist: Brotherhood, remarking that "we learn a good deal of recent history in a short time that paints a picture of exactly what’s going on".

[35] His second fight against the Elric brothers in the manga and his confrontation with Winry Rockbell were praised by Sakura Eries from Mania who found the former to have its "own surprise moments" while the latter had her "on the verge of tears".