Ares didn't need to challenge Riven's father.
Once he saw Ares shift and begin to make his way to him, blood oozing out of every wound on his body, he did what needed to be done. He knelt on the rain-soaked floor, gaze pointed to the ground and neck exposed.... submissive.
He was willingly handing over his pack to Ares...
The area was silent as the realisation spread through every one of us, hearts beating almost in sync as we waited for what Ares would do. He could either take Riven's father's life or leave him to become an unranked member of the packs once they united. The risk was great for both - if Ares took the life, some would see him as heartless, they would question his judgment and it would do no good but sow seeds of doubt in his new pack members. But if he didn't take the life, there was a possibility that some would stay loyal to their original Alpha, begin to plot against Ares...
It was a tough decision, but I trusted him to make the right one...