Simon also seems to be making progress with Isabell, at least until you learn that he also meets with Maia. The mark on his forehead makes him indeed run through the streets during the day, but he is in no faction really welcome or appreciated.
At last the normal Dating / Couple madness for all to touch seems close, but since the first dead Shadowhunter is found. And he will not remain the only one.
If Jace begins to hurt Clary in his dreams and kill, the disaster takes its course.