The Camaraderie

Atreus aka Kahn finally understood why he was sent here after his master, Romulus said that he wanted him to learn how to become a War General. 

Previously, he spoke of the part where he expressed his opinion about Kahn learning how to lead. 

But 'Leading' didn't always mean taking charge in a battle. It also meant clearing a path and cooperation with your allies to take down the enemy side. Like how a captain of the Cavalry often charged at the front of offense and created a path for his subordinates in a battle formation to decimate their opponents. 

Kahn had no problem doing so with his subordinates but Dorian was a different case. He wasn't an ally with no fear for his life and neither was he Kahn's puppet who would obediently follow his orders without questioning his judgment.

So maybe he was sent by Romulus here to learn that very aspect as a comrade during a battle. Something he never had experienced before.