“It matters to me. That's what you don't get. You can't understand. You can't understand what it's like knowing what I did. That whole time being Strigoi...It's like a dream now, but it's one I remember clearly. There can be no forgiveness for me. And what happened with you? I remember that most of all. Everything I did. Everything I wanted to do.”
After Dimitri becomes a Damphir again after Lissa saves him, he is wracked with guilt. In previous books, he has expressed that he would rather die than become a Strigoi as it is the equivalent to losing his soul. Indeed, it seems that the guilt is too much for Dimitri. He has always been portrayed as levelheaded and a bit of a pacifist, despite his job, but the fact that he acted with so much carnage and bloodlust is not something he can bring to forgive himself for. Indeed, in other books he was shown to be a regular church-goer – it could be that religiously, this has impacted his values as he believes that he has committed the biggest sin – killing innocents.
“I'll find you. There is no place in this world you can hide from me. I'm watching.Love, Dimitri”
Here you can see the drive that Dimitri has in his quest to turn Rose into Strigoi. Despite the fact that she is a Damphir and therefore as Strigoi he should feel nothing for her, it is clear that even in this form, a part of Dimitri still loves her. Indeed, he seems to be slightly obsessed with her and this is in stark contrast to his appearance in the previous books where he constantly tried to to escape his feelings for her and it was her pursuing him. It seems, its now Rose who is trying to run from him, and Dimitri is the one who wishes to be with her.