Satan: Tragic Hero or Just Tragic?

We all know Satan is the bad guy in Paradise Lost. That much is indisputable. Despite that, we feel sorry for him throughout the events of the story. That's because he is portrayed as the protagonist of this story. When he falls from grace (literally), there is a brief moment where he wallows in his own misery: crying about a fate that he brought upon himself. He then is faced with moral conflict when he considers going back to Heaven and begging for forgiveness, but instead, accepts his nature and resigns to his fate of forever being the bad guy. However, just because we are to pity him, that doesn't mean that we are to excuse him for what he did. He did some unforgivable things, that much we know, but yet, he is portrayed as someone who just accepted who they are, instead of changing himself. Satan may be supernatural, but he is the most "human" character in the story, because he is accepting of his flaws and he knows that changing his own nature just isn't going to happen. His nature is his tragic flaw and is the reason he is the tragic "hero" of the story. His nature led to his downfall, and is preventing him from pursuing the redemption he is hoping for.

Edit:  Commented on Gray's and Mackenzie's posts