For me it’s all about Wolves, they are initially portrayed as the villains of the story, they are the killers, they need to be hunted and slaughtered for what they have done.
Sloan after hunting the wolves tells of seeing them devouring one of their own children.
He explains they are only be doing what they need to survive, they have no option when starving in the harsh freezing mountains of Alaska, whereas the humans are the senseless killers, people have options if they cannot look after a child, social services or adoption, wolves do not have that option.
The film starts with the savagery of Iraq, rape and murder are shown as everyday life, our hero returns from active duty injured to exact revenge on his wife for the murder of his son, but there’s more to our hero than we expect. He is no hero just a twisted psychopath hunting his equally deranged wife. Killing all that stand in his way.
At the end the wolves are there again, but they do not attack Sloan, and for me, just like he is not killed in the cave by our now non hero, Sloan exudes a persona that portrays innocence. He is also spared the machine gun massacre as well.
Sloan gets what he came for in the end, it’s reconciliation with his estranged daughter.
There’s just a lot of senseless violence on his journey, not by the wolves he’s asked to hunt, but by the people that asked him to hunt the wolves.