After One Direction's Madison Square Garden concert Monday night, Harry, Niall Horan, Zayn Malik, Liam Payne and Louis Tomlinson hit up New York City's Hudson Hotel with the "I Knew You Were Trouble" singer for some late-night fun.
Taylor herself had just come from a gala where she was honored by—awkward alert?—ex Conor Kennedy's family.
In a series of blurry pictures, Harry, 18, and Taylor, 22, can be seen holding hands as they show off their vocal skills. An eyewitness tells E! News Taylor "spent the early part of the night hanging out with the parents, but once karaoke came on, she and Harry joined [other 1D members] onstage for the rest of the night." For one of the last karaoke songs, Taylor and a gal-pal sang a One Direction song, according to a witness.
A One Direction fan account on Twitter captured Taylor and the guys paying homage to another boy band: the Backstreet Boys! In one shot, Taylor, Harry and Niall appear to be quite invested in a karaoke performance of BSB's 1998 hit "I Want It That Way."
"Haylor is real, y'all," Sunny Jacob, a 1D fan, tweeted along with a picture of the duo.
A witness tells E! News Emma Roberts and a girlfriend were also in attendance at the karaoke get-together. At the end of the night, when the light cames on, the One Direction guys, Taylor and pals took a turn on Playstation. Harry and Taylor "were clearly having fun," says a witness.
Later on, shortly after 4 a.m., Harry and Taylor, holding hands again, were spotted going back to the Red singer's hotel.
The next morning around 11:30 a.m., Harry and Taylor were snapped leaving the Greenwich Hotel separately.
Live while you're young, kids!