Like I said in my review of The City of Bones, we see the possibility of the family issue being resolved to the happiness of our little tragic couple (it really seems like they came out of a Greek tragedy).
After stealing the Cup in book one, Valentine manages to steal the sword as well. Both being very important Shadowhunter objects of power necessary for them to perpetuate their line.
Of course he wants to use them to gain control of the Shadowhunter world and kill all demons and Downworlders then (those being the werewolves, vampires and fae) even though there is an uneasy truce between SHadowhunters and Downworlders – demons being the creatures bent on destruction and not belonging to our world.
So, Jace being Valentine’s son has to deal with the backlash of the pretty much whole Shadowhunter community and I must say, I didn’t expect him to behave like a grown person and was very much surprised when he did. Pleasantly.
The reason I am so eagerly waiting to read book 3 is because we get several hints as to the possibility Clary and Jace are not brother and sister (yesss!) and it ends with the possibility of Clary’s mother waking – so with cliffhangers like that, I’m off to see what happens next.