The second single from Love Is Cool is an ode to friendship. It is a reworked version of a song originally released by Wolf Alice in 2013. Singer Ellie Rowsell said: "'Bros' is a sentimental tune to us, it's grown and changed with us over the past couple of years, taking on different shapes and forms until it evolved into being this definitive album version. It's an ode to childhood imagination and friendship and all the charm that comes with that. The live response to the song has been truly humbling."

The song's music video was filmed in Finsbury Park and Holloway, North London, where Ellie Rowsell grew up, and directed by 'Sblood - the team behind the band's "Giant Peach" clip. The visual shows two young girls playing together in a local park and cafe. "It's an ode to childhood imagination and friendship and all the charm that comes with that'," said Rowsell.

The first home demo that Ellie Rowswll made was an early version of this song. She recalled to Tonedeaf.com: "I put it on Soundcloud and Huw Stephens (BBC Radio 1 DJ) played the home demo even though I didn't have a manager or record label or radio plugger, and I was like 'what the hell? how did he find this?' I remember thinking 'ok this song must be good if he's picking up a home demo on my Soundcloud without having heard of us or anything.'"