Dmitri is great actually. We've given him a fair lot of dragon traits now that we think about it so that'ssss... Something to consider. Grigori's also something to consider. I'm 90% sure he's not human but I have no clue what, exactly, he is.
So, the thing with our Grigori is... He's just not human. But no one knows what he is and he's convincing enough on the surface level. He's immune to Siren Song. He doesn't get hurt easily and heals ridiculously fast. He has no childhood memories, no family on file, nothing. His dedication is to Dmitri and Dmitri alone- The Wall only matters to him because Dmitri cares for it. The cold doesn't bother him one bit, doesn't even shiver in -10 weather, but he bundles up anyways because it's a good example. I Cannot Get My Head Around Grigori what the hell is up with this guy /pos.