The books feature a group of teens with different superpowers.
The last book is set in New Orleans and is about a girl who can feel people's emotions and control them.
After she gets a taste of crowd control and the evil side to it, she is introduced to the protagonist.
She is ends up getting that crowd to kill someone.
Is this the Zeroes trilogy by Scott Westerfeld...?
According to a Goodreads user review, the books are about a group six super powered teenagers, two of whom have the ability to affect the mood or will of crowds.
Nate/Bellwether (aka Glorious Leader) has the ability to bend the will of crowds, to make them follow him.
Chizara/Crash can crash anything electronic, hence the name. But the downside to her power is that even being near electronics hurts her to her very bones, makes her brain itch.
Riley/Flicker is blind, but can see through the eyes of others.
Thibault/Anonymous finds it incredibly easy to disappear, but the flip side of this is that no one can remember him unless they’re looking at him. If any more than five people are present, he becomes downright invisible. Ironically, one of the most memorable characters.
Ethan/Scam can open his mouth and let another voice take over. Another voice which knows truths about the people it’s speaking too, truths he would have no way of knowing. But it gets him into trouble.
Kelsie/Mob can affect the mood of a crowd, making them feel better, happier, more alive. But it can also have a negative affect, redoubling anxious or fearful emotions.
The synopsis of the third book notes that it's partly set in New Orleans.
Meanwhile, Sonia Sonic and her growing band of weird-hunters are tracking inexplicable events across the country - and their investigations lead them to New Orleans during Mardi Gras, where the celebrating crowds promise enormous power to anyone who can channel it. Time is running out for the Zeroes, but they must learn to trust each other again and combine their powers for good - to avert the looming disaster.
