The Tactical Siblings

From the hidden depths of darkness and loss, a young Inkling boy carved his way into the center of the great city of Inkopolis. His heart was drawn there to the flame of battle, to fight for glory and for his parents' ancient honor. He had come to establish his name, and he would rise through every day as a monument to victory. Surpassing all the others in the city, would not any challenge prove his proficiency to all who stood below her?
Yet, for all his skill in battle, he would come to face one whom he could not take down. He would come to face the epitome of skill. For the first time in his life, he would be tested beyond his limits. He would come to know the evils of war and the pain of deep loss. He would once more share darkness.
Could a bond, forged in secret whispering of old wars, forged from a shared cause that threatened the honor of all Inkling kind, save two lost hearts from despair?