Twilight: Starlight, you have no idea what you’ve just done.  
Starlight: The gem in her necklace. It’s connected to King Sombra.  
Twilight: Yes, carved from the same crystal in which King Sombra was sealed. In destroying it, you’ve broken that seal.  
Starlight: And set him free. But for some reason, he doesn’t scare me anymore.

Starlight Gets ready to blast Chrysalis, until Twilight notices the black crystal around Chrysalis’s neck. 
Twilight: NO, STARLIGHT, DON’T! 
Too late, because Starlight blasted Chrysalis, shattering the crystal. Later, we find out this releases Sombra, as Twilight explains. Starlight’s response? 
Starlight: For some reason, he doesn’t scare me anymore.

@Background Pony #9A04  
They decide to stay because they’ve lived in this village for a long time. They have gotten to know each other in that village, and in some cases did become friends. After their Cutie Marks are restored and Starlight gets kicked, the villagers now see a new opportunity to further get to know each other. And in the case of Double Diamond, Party Favor, Night Glider, and Sugar Belle, they have each seen the other’s special talent contribute to the solution.

That was something I couldn’t stop thinking about Starlight’s town. If everypony hated what she was doing why did they all decide to stay after she left? Don’t they have homes and family to go back to? I think they were all like Troubleshoes, all too happy to be rid of their marks. And if he was there when the town drove Starlight out he would have had the choice of going back to live in that lonely cart in the woods, or stay with ponies who had the same problem he had and could understand him.

@Background Pony #8FC8  
We don’t know the Princesses’ backstory very much. However, the ponies adore Celestia and she wants to be the kind of leader the ponies would desire. And Luna after her restoration also wants to be that same sort of leader. Perhaps when the Movie comes out we’ll get some more information on the Princesses’ history.

I wonder how many ponies that are ruled by Celestia elected her as her leader. Or how many had a say in anything the princesses do.