Halsey performs at the Austin City Limits Music Festival in Zilker Park on Sunday October 11, 2015. JAY JANNER / AMERICAN-STATESMAN

“I write songs about sex,” the dour, 21-year-old singer said from Austin City Limits Music Festival’s HomeAway stage during her Sunday set. “I write songs about being sad. I write songs about the human condition.”

Halsey knows her brand.
That brand is “clumsily churlish sulk-pop,” and it moves the masses. In the brow-wetting midday heat, a crowd bulging at the seams chanted “Hal-sey! Hal-sey! Hal-sey!” as set time approached. Signs held up high in the audience read “Slut for Halsey” and “I missed my senior homecoming for this.” When the singer emerged from backstage, the spitting image of “True Blue”-era Madonna, she met the euphoric screams with a curt “Thank you.” Halsey launched into “Gasoline,” and the caboose of a hand-holding string of teenagers let out a squeal like she just got a new iPhone.
“Are you deranged like me? Are you strange like me? Lighting matches just to swallow up the flame like me?”
The songs from this year’s “Badlands” LP are a study in a peculiar ennui, the kind articulated by young Americans who have the resources to feel misunderstood alongside their closest friends for a couple hundred dollars. Halsey flanked herself with red, white and blue as she sang about selling her soul to a “three-piece” that’s got her down on her knees. Images of drowning recur, lyrically, and sparse, moody trap beats recur, rhythmically.
There were few dimensions from song to song. This was not pop music meant to be enjoyed — this was pop music with which to identify the ways you are misunderstood because you are weird and dangerous and dangerously weird. One shade of sullen, carefully optimized to encourage ticket sales.
“And I’m gonna write it all down, and I’m gonna sing it on stage/But I don’t have to f****** tell you anything, anything.”
After sorta-confessing that she has “done some things she just can’t speak,” Halsey said she wanted to see Austin bounce. She said it in the way one might say they want another cigarette. But she was a champion for her flock of wildchildren. The heat punished, so she stuck out two water bottles to a guy working security.
“My good sir, could you give these kids some water?” He didn’t turn. Halsey bristled and grew chillier. “I’m talking to you, homeboy.” That showed him.
“Roman Holiday,” Halsey said, was a happier tune. In it, the narrator’s father punches through the dining room wall, but it’s mostly a weary-eyed look back at young love and having sex in the back of cars. When Halsey moved to the wings of the stage for an interlude, the camera followed her like a child that took instructions to “stay near me” hyper-literally and followed its mother into the bathroom. The audience craned its next to see any trace of what Halsey was doing. On “Hurricane,” she reminded the audience that they don’t belong to anyone but themselves. They met her with moon-eyes.
Halsey introduced her last song, “New Americana,” as a satire, which it’s not. “This song is about the power of a youth collective just like you,” she said, singing of legal marijuana, Biggie and Nirvana. Astride the barrier separating the audience from the stage, she looked like a student revolutionary from “Les Miserables,” rallying her brigade to care and not care at the same time.
The set ended early, but the crowd still chanted. If you turned back to see if Halsey had returned, you would not have seen a close-cropped, platinum blond head saying an affectless “Thank you.” You would have seen kids screaming like baby birds for set lists and towels thrown down from the stage by crew members.
“Survival of the richest, the city’s ours until the fall. They’re Monaco and Hamptons bound but we don’t feel like outsiders at all.”

A rebel with a world tour.