From Final Fantasy Wiki

Yaag Rosch

"Tell me, do you really think your life is worth more than the lives of millions of Cocoon citizens?"

—Yaag to Snow

Lieutenant Colonel Yaag Rosch (ヤーグ ロッシュ Yāgu Rosshu) is a character in Final Fantasy XIII. As his title implies, he a PSICOM officer, and he was Lightning's superior during her military service. He graduated second in his class, just behind Jihl Nabaat, but had a hard time in the military academy. He often fights in the front-line with common soldiers, and the scar on his forehead reflects this. He carries a saber.

Developers have stated that he is not the main antagonist, but rather a recurring rival, and is the "right-hand man" of Jihl in the story. His design was overseen by Nao Ikeda, supporting character designer for Final Fantasy XIII.

Unlike Jihl, Yaag seems to have doubts about the government, and sympathizes with the l'Cie. However, since he desires to protect Cocoon's citizens above all else, he becomes an enemy of Lightning and her group.

At the Eden catastrophe, he rode the machine "Proud Clad" to fight the protagonist party, but lost and was fatally injured. He ceased to be an enemy of the party and asked them to protect Cocoon. When the party left and two King Behemoths reached him, he sacrificed himself to kill the monsters.