We're beginning to think that Simon has no last name because Clary, the worst best friend ever, doesn't even know it. Simon is the friend who would "always be standing underneath [the jungle gym] to catch her if she fell" (3.13.85). Clary not only wouldn't notice if Simon fell, she'd probably be the one pulling his fingers loose.
In this installment of the Mortal Instruments, Simon kisses Clary (and she lets him, even though she doesn't want him), he gets humiliated in front of the Faerie court when Clary kisses Jace, he dies, becomes a vampire, then dies again, then comes back to life. Again. Simply put, it sucks to be Simon, and that's not a vampire pun.
Okay, Simon has it hard, but the best thing that could happen to him is that he becomes a vampire. It's sad at first, giving us the most tear-jerking line in the whole book when Simon is reborn:
Simon, who had been a vegetarian since he was ten years old, who wouldn't drink milk that wasn't organic, who fainted at the sight of needles—Simon snatched the packet of blood out of Raphael's thin brown hand and tore into it with his teeth. (2.10.72)
But it gives Simon a power that he never before had, and puts him on equal footing with the supernatural Shadowhunters he's found himself with. Previously, Simon was an outsider in a social circle he never asked to be a part of. Now he's just as strong as them, if not stronger. He also becomes emotionally stronger by finally ditching Clary as a love interest, which was a one-way dead-end street, and starting to forge a relationship with the werewolf Maia.
Simon's powers get even more potent—and weirder—at the very end. Once again, Simon gets killed, this time by Valentine's sword. But Jace finds Simon on death's door, and feeds him his own blood to save him. By drinking Jesus'… er, Jace's blood, Simon develops an immunity to sunlight that no other vampire has ever had. He can walk around in the daylight. We can only wonder where that will take him.