I have always been fascinated by friendships, in particular female friendships. One of my favourite films is Peter Jackson’s Heavenly Creatures, which is about the notorious 1954 Parker-Hulme murder case in Christchurch, New Zealand. This true-life story of two young girls who, after a series of events, end up murdering one of their mothers is not something I can quite relate to, and yet their intense relationship and obsessive admiration for one another – filled with love, jealousy and even the creation of a mutual fantasy world – is something I completely recognise in my own life, and that of the girls I grew up with.

I went to an all-girls school in north London founded by Frances Mary Buss, a pioneer of female education. This relatively small school taught us to celebrate all that comes with being a woman, and the absence of boys meant that “gender roles” were not something I was ever aware of. Don’t get me wrong, I was devastated by the fact that my only contact with boys for five years was the occasional wave, duck and hide at the skaters in the park opposite the school, but, in hindsight, I’m eternally grateful: it is these experiences, surrounded exclusively by hormonal teenage girls, that have continued to inspire me in both my life and my work. If I have ever known what it means to be loyal; to be jealous; to admire and to obsess; to feel love and to feel hate, it never was as intense as with my girlfriends.

I have to admit, when I was writing our song “Bros” I wasn’t thinking too heavily about the complexities of female friendship, but rather pondering on my childhood with my neighbour and friend, Sadie. We went to the same primary school, and although we were in different years (she liked to remind me that I was going to die first because I was older), we were best friends. Like Heavenly Creatures’ Pauline and Juliet, Sadie and I spent a lot of our time playing “pretend” or, as they say in the film, immersed in “the Fourth World”. I think it was this, along with the beauty and power of a child’s imagination, vivid enough to invite your friends to be a part of (though ours was more Rugrats than Heavenly Creatures), that inspired me lyrically.

I’m not really one to write simplistic and jovial lyrics, and while on the surface I can see how “Bros” is a happy song – a celebration of friendship and one’s younger years – I see a panic in the words. Particularly the bridge, which I think expresses the fear I had, not of growing up, but of growing up without Sadie. I don’t know which one of us started having trouble entering the Fourth World first – I’d like to think it was me because I was a year older, but I don’t think our age difference was mirrored in our maturity. Either way, I worried that once we entered reality as budding adults – no longer pretending to be “raised by wolves and other beasts” – we wouldn’t be together all the time. Would we still sleepover at each other’s houses, not wanting to go to sleep because in dreams we couldn’t chat? Would she make plans without me? Would I make plans without her?

These are fears we all grow up with, and they’re not exclusive to girls. But ever since I left school I have lived in a heavily male-dominated world. I worked in a men’s sportswear shop for a year or so before entering the music industry, in which I feel I spend most of my life on the road in very close proximities with all-male bands and crew members. This was a big change from my heavily female-dominated teenage years, and I do not come across the same complex and intense relationships as I did then. I know that this is largely due to the fact that I am no longer a teenager, and the world is slightly less confusing (although equally as fucking scary), but could it also be because I spend most of my time with boys and men now?

I have slowly drifted from my school friends and while that invisible tie that keeps us together – though we are miles apart – is still there, I miss the intensity of our friendship, our female friendship. I feel as though I am constantly searching for that again, and I wonder if no lover, no male friend and no amount of people I put on the “guest list”, will ever match that experience and that feeling. There are dark sides to these intense, all-consuming friendships, and I suppose I was right to be worried about Sadie making other plans. She did, so did I, and I don’t see her half as much as I’d like to. But when I do we are still very much Bros, and the fact that people often ask us if we are speaking a different language when we are together suggests we can still very much enter our Fourth World.

Ellie Rowsell is the lead singer of the band Wolf Alice.