Boybands go through cycles. Most start out manufactured to look clean-cut and to peddle high-gloss pop before evolving over the years as members get more individualistic and adopt rougher outlooks in image and song.
Judging from their debut Singapore gig at the National Stadium on Wednesday, English-Irish quintet One Direction are one act firmly in the latter stage.
They are hardly the same group of teenagers brought together by The X Factor judges five years ago; the quintet - Niall Horan, Zayn Malik, Liam Payne, Harry Styles and Louis Tomlinson - are now young men in the early 20s.
Vocally, they still harmonise well, save for Harry's slightly hoarse voice, and each of them seems to have developed their own distinctive attributes, too.
There's Liam, the joyful-looking one, permanently in high spirits and making corny little jokes; Louis, the one with a twinkle in his eye and a cheeky demeanour; and guitar man Niall, who switches between his Gibson SG electric and an acoustic and, when he hasn't got a guitar strapped on, constantly raises his hands in glee.
Harry and Zayn are the two relatively serious ones.
Long-haired Harry's the obvious heartthrob who gets the most deafening screams from the fans despite skulking around with a semi-permanent scowl and an intense look on his face.
Zayn, the scruffiest of the lot, is rakishly thin and hardly cracks a smile. He also happens to be the one with the most soulful singing voice.
With such a diverse mix of personalities, it is no wonder One Direction do not do synchronised dance steps. Each does his own hand moves or little jigs as they all ran around one another on the massive stage and its extended runway.
Musically, their newer tunes taken from the latest album Four (released only four months ago) sported a jagged difference from saccharine past hits such as debut single What Makes You Beautiful and One Thing, which drew the biggest cheers.
Where Do Broken Hearts Go and Clouds have shouty, meaty choruses that would not sound out of place in the oeuvre of 1980s hair metal bands. Such is the sound of a boyband wanting to trade the lightweight tone of their earlier discography with heftier and more substantial jams.
Their fans are growing up, too.
While fans of primary school age could be seen here and there throughout the stadium, many of the rest have, like One Direction, blossomed into young adults. Hence the bras thrown on stage, almost tripping Harry at one point.
Burgeoning sexuality aside, One Direction are not quite plying their trade in sex, drugs and rock 'n' roll yet. But they sure look ready to steer further away from their high-sheen pop roots.