Elliot is not okay. Elliot can not save dead children the way he saved himself. Hitting Plover with a bus will not save children whose skeletons are rotting in a cellar. They will never be able to look at the mangled bodies of the people who hurt them and think "It's done, I'm free", reinvent themselves and pretend to move on.
That doesn't stop him from wanting to wring Plover’s neck with his own two hands, no magic involved, and actually feel the man’s, the Beast's, heart stop beating, but the man is the beast and it will take more than his two hands to stop him.
Fillory was not meant to be his fight. It was a joke and the beast was something to tease the puppy-dog cute freshmen with. It is his fight now and he will not stop until he is o'ershoes with the beast's blood. Until his face is wet and red and sticky with Jane and Martin's vengeance.
This death will not be remote. It will not be a dull, wet, smack and a distant crunch, red streaked across the pavement and a greyhound driver's traumatized face. It will not be a series of cracks too fast to differentiate as the neck of a missing third year snaps across the room and the empty shell of a boy from Texas who liked piss water beer crashes to the ground like so much carrion.
So maybe, this vengeance isn't just for Martin and Jane. Maybe, it's for him, too. Maybe, it's because he's terrified that if that man in Indiana hadn't left something unfixable broken inside him (all the children at Brakebills are broken, broken and pretending to be grown up) he wouldn't have let the beast into their lives so easily. Maybe, it's because he has to make up for Penny almost dying somehow. Maybe, it's because after all this he doesn't know how to pull his heart out of the pit of cynicism and distrust that has made its way into his chest.
Killing the Beast, this predator, will not be easy. So during the day he will take his study as seriously as always and continue to pretend that nothing matters. At night he will drink, fuck, and smoke himself to sleep; it is better than lying awake with memories of a hand between his thighs and never one over his mouth, farms are large places with no one to hear you scream.
Even alcoholic stupor can't wipe away the thought that in Indiana the famous children of Fillory would have never needed to worry about having their mouths sewn shut.