Having been sent back to Romdo, Iggy starts to contemplate his purpose. After all, his sole reason is to serve Re-L and she has expressed a desire to act without his assistance. This, coupled with the fact that he's infected with the Cogito virus (and has apparently been so for some time) drives him more than a little crazy.
The end result is amazing. Iggy is extraordinarily creepy as a villain and it makes the episode incredibly gripping to watch as a result. He captures her and proceeds to verbally rip into her something fierce. It's a jarring switch from the normal, calm, pleasant Iggy that we knew, but he really seems to loathe her, holding nothing but contempt for her. At the same time, he is still loyal to her and a lot of his rhetoric is reminiscent of a stalker or some obsessed ex-lover.
Even his desire to kill Vincent is tied to him wanting to keep Re-L to himself. Seeing as it was Vincent who set everything in motion, in his mind, killing him will end everything and things can go back to the way they were before.
Both Iggy's spiteful monologue to Re-L and his standoff with Vincent are rather tense. It really was a lot of fun to watch.
The other autoreiv from before makes a return appearance. While he doesn't do a lot for a majority of the episode, he does express a desire to kill Re-L. It leads to Iggy sacrificing himself to protect her.
If you were thinking there was going to be some sort of redemption, you'd only be about half right. It seems Iggy's gone schizophrenic as he goes back and forth between asking Re-L not to hate him and continuing to hurl vulgarities at her.
To Re-L's credit, she seems to show sympathy for him despite everything he's done. Honestly, after all that she would have been more than justified if she had told him to piss off and punted his now detached head out into the tundra.
I really did love this episode. It was creepy; it was tense; Iggy made for a fantastic villain. I kind of wish they had found a way to keep him alive, but his end worked. Even the philosophical stuff that comes into play works well. Iggy starts to make the argument that he has a soul now and chides Re-L for thinking otherwise. Even if you disagree, it was a compelling point and it made the episode that much stronger. This is probably one of my favorite episodes of the show overall. While there's still ten more episodes to go, I'd be surprised if that wasn't still the case by the time we reached the series' end.