Amid rumors of a solo career, Harry Styles might have written another song for Ariana Grande without One Direction again.

Renowned producer Johan Carlsson, who co-penned "Just a Little Bit of Your Heart" off Grande's debut studio album "My Everything" with the British singer, recently revealed to Daily Mail that they were "just writing songs and seeing if we can come up with something cool."

He also confirmed that they worked together "on and off several days a week for four weeks" in a private Los Angeles recording studio before Styles went on his band's "On the Road Again" world tour, kicking off in Australia.

"He's such a good songwriter -- it's an honor to write music with him," Carlsson added. "He's fantastic with the words and he can really put down lyrics that are very conversational and people can relate to. We're just having a good time."

HollywoodLife.com recently reported that the 1D heartthrob might leave his bandmates and pursue his solo career. He also wants to have a new, more mature image.

"Harry would love to break out on his own as a solo artist. He really wants to get away from the teeny-bop stuff and sing a rock record," a source said. "When he first auditioned for 'X Factor,' he was a huge fan of English rockers Oasis and wanted to sing rock anthems just like them."

With that being said, Styles has apparently been working toward his ultimate goal. "He's recorded with different producers in London and in Los Angeles. Although he doesn't want to completely alienate his fan base, his new music is a lot edgier," the source added. "Harry's One Direction bandmates have been waiting for the day he quits to go solo and anticipate it happening in the near future."