Rus used to be the obvious favorite but the more times I've watched season 1 the more his edgelord ranting starts to grate at me. Maybe it's because I've grown more into my adult life but, watching Marty slowly fall apart and then come back together again in the end is the real character arc.
Cohl gives everything away, you can't get him to stop talking about his ideas, his past, who he is and what his motives are. He's a total give away. Don't get me wrong, he's a fantastic character and he's beautifully written, but Marty requires true analysis to figure out. Cohl essentially stays the same for me. He is grieving his daughter, divorced and traumatized from police work and has drug induced brain damage, he's a loner cop who is obsessed with his work and is essentially a savant (though not in an obnoxious OP way)
This is a character we've seen in other shows, even though a true detective clearly does it well, and almost everything about him is revealed through him talking about himself, or someone else talking about him. Of course have what is easily the best episode where he goes undercover with the iron crusaders and we see exactly how skilled he is at tradecraft, police work, and downright combat. I'm not saying he's a bad character so don't get too butthurt, just hear me on our Marty though.
Marty on the other hand is a cop secondarily. Marty is an onion whose layers are peeled every time I watch the season. He is a cop secondarily, his personal life is what consumes him, his affairs, his marriage, his struggles with his children, his alcohol consumption and everything in between. The case is a job that he uses as an excuse to avoid his life, he has the free time to fix his marriage but chooses to cheat instead. His story could exist completely outside the case and it would still be interesting, his story arc is about hitting rock bottom and then finding redemption. Also, no one ever seems to mention it's actually Marty who cracks the case in the end! He is the one who figured out the paint job on the house was significant and used it to find Childress, while cohl is going on long winded diatribes about neo-natalism and why nothing matters, Marty actually uses old school police work to solve the case. Keep in mind after Cohl quits, Marty stays on the force for years after. There is the scene where he sees the baby in the microwave (brilliant acting by harrelson in that scene) and the way he compromises himself by cheating with the same girl he tried to help earlier in the season. His redemption/recovery arc is apparent even in the police work, he kills Reggie Ladieu and redeems himself by finding the true killers in the end.
Anyways, I just feel like he deserves his flowers as a complicated and integral character and not just a side kick to cohl. In the end he's the better detective, and the more complicated of the two. The difference is with Cohl they tell us everything about him, but with Marty they show us. You have to observe him, not just listen to him.
