In this episode, we learn that the Clave executes death row prisoners by burning them alive. Clary describes the practice as barbaric, and I definitely agree that it's messed up. The idea that they put a large number of people to death in one go and that the consul stands there and coldly watches the whole thing with no concerns blows my mind. Honestly, I know the show has been canceled, but if it had gone on longer, this is something I'd want the show to come back to and make the Clave improve on.
Simon learns that it's the Mark of Cain on his forehead in this episode. That isn't news to anyone who's read the book, but since he knows exactly what the mark is when he receives it in the books, it's interesting to watch him figure it out in the show.
Lilith seeking Heidi's help was a good idea, but it's frustrating to watch Heidi fall so easily for Lilith's manipulation while thinking she's empowering herself. Watching Heidi threaten Simon's family was particularly difficult. Both because the blood made me squeamish and because it's just sad to watch, especially when Simon's mom begins yelling at him that he's a monster.
Clary uses a rune to bring Valentine back to life, which is kind of terrifying as well. That's the kind of power that no one should have, and as far as I can remember, it's not mentioned again after this episode, which is kind of wild if you think about it. It's something I'd imagine becoming extremely classified, with Clary being forbidden to share the rune with anyone in the future. If I were part of the Clave, I'd certainly be worried about her being capable of such a thing.
Between bringing back the dead and Simon's family calling him a monster, this was an intense episode, but I really like how they did it.