Glass Ending Explained (Spoilers)
Elijah got lucky. When he destroyed that train which forced David to realize he had superpowers, he also killed Kevin’s father. The one person in his life who could keep his mom from going off the deep end. Yet, with him gone, the abuse continued and so gave birth to Patricia, Hedwig, The Beast, and many others. All of which Elijah was hoping wouldn’t be revealed until he and The Beast got to a more public venue for The Beast and David’s rematch. One at a newly open tower, the crown of the city, that Elijah was threatening to blow up.
However, before that can happen, a few things go down. First and foremost, Joseph reveals Elijah is the reason Kevin’s dad is dead. Thus The Beast kills Elijah. Well, he breaks his shoulder and punches him in the sternum hard enough to cause internal bleeding – which later kills him. This allows David and The Beast to continue their fight, which was already in progress, but they don’t get to kill each other.
Nope, here is what happens: What we assume to be the cops arriving to stop the fight, are anything but. Rather than stop the fight they drown David and after Casey is able to bring Kevin to the light, they shoot him and he dies. Yeah, rather than The Beast and David, The Overseer, fighting to the death, a mysterious organization, of which Dr. Staple is apart of, has them both killed when they get the opportunity.
Now, who or what is this organization? Well, all we learn is they identify each other by a three-leaf clover, and their goal is to be neutral in the battle between good and evil. Not in terms of arming each side, but killing each side – if they have to. The preferred method is dismaying them from the idea they are all powerful, but if that doesn’t work, they have to die.
Leading to them erasing any evidence of what happened, or at least them thinking they did. You see, one of the worse things you could give a man like Elijah is time and a challenge. Elijah spent 19 years away in a mental ward and suddenly had a few days, a time limit, to break out. Also, he was told there were cameras all around, watching. So, he decides to prove what he has long known by using those cameras to record all that happened and send it.
Leading you to ask, who did Elijah send the camera feeds to? Well, to the people no one would believe. He sends a copy to Joseph, his mother, and Casey. Three people who, together, decide to upload the videos and watch the story go viral. Thus destroying the work of the Cloverleafs who have tried to keep the idea of people being superheroes as delusions and ridiculous. However, with seeing The Beast and David in action, this has become false and with Dr. Staples noting there are others she has dealt with, more to come, so opens the door for a whole new story. Either taking place after or before the events of Glass.