Lucie Herondale and Malcolm Fade
I can't stop thinking about one interesting fact. Careful, spoilers for LOS and COG!
Blackthorn Hall ("Chiswick house"), 1903. Lucie met Jesse there and picked up a small crystal that looked like a fake diamond. After that for a moment in the shadows she had a vision of an ashy blond young man, he seemed to her vaguely familiar. ("Chain of Gold", chapter 6)
Same place, 2012. Ty, Livvy, and Kit went to Blackthorn Hall in a quest to find clues about Annabel Blackthorn's whereabouts and found an aletheia crystal. After that for a moment Livvy had a vision of a brown-haired woman who looked like her. ("Lord of Shadows", chapter 18)
Looks like Lucie has seen Malcolm Fade from the aletheia crystal. And if she knew what was it, her generation could expose Malcolm, prevent Annabel's resurrection and Livvy's & Robert's deaths at least.
Lucie may know him from some book. She is so in ave with love stories...
UPD. Okay, Lucie knows Malcolm in person and briefly had a crush on him. Then it's even more understandable why she almost recognized him.