Sia released her second collaboration with Kanye West on Thursday (Jan. 7), unleashing "Reaper" into the world.

The song, off Jan. 29's This Is Acting, was originally meant for Rihanna's still-unreleased ANTI, but although Sia has provided songs like "Diamonds" to Rih, she passed on it.

"Reaper" almost didn't make the cut for Sia's upcoming LP either. In December, she told Rolling Stone, "I'm not emotionally attached to it. I thought it was a fun song. I think it's a good, fun song, but I didn't anticipate it being on the record. But my manager really likes it so I put it on for him."

'Ye co-wrote and produced "Reaper," but the "Chandelier" singer has admitted that she and Kanye weren't in the same studio when they made it. Sia and Kanye's first song together, "Wolves," was never officially released, but it was performed at "SNL 40" with Vic Mensa.

"They'll entice me into a session by saying, 'Rihanna will definitely be there' or 'Kanye will definitely be there,' but it's hilarious because I turn up and, almost always, they never come," she told RS. "So I went into the studio to write for Rihanna with Kanye and neither of them showed up and stayed for less than an hour. They had two tracks. They told me what they had wanted. There were notes from Kanye, and I can't even remember what they were."