It was a line dropped into Hellblazer #51 in 1992 by guest-writer John Smith, with John Constantine talking about his life. It was the kind of line that regular series writer Garth Ennis would never have used. Not back then at least.
"Girlfriends… the odd boyfriend… they all have a nasty habit of walking out on me." And establishing John Constantine as DC Comics' first lead queer character. This is the closest Garth Ennis got in that regard with the character.
His bisexuality was never made explicit a decade later when Brian Azzarello wrote Ashes and Dust in the City of Angels in 2002, depicting a sexual relationship with a man he is manipulating in a BDSM club.
At which point, mentions of past relationships with men as well as women begin to be more frequently mentioned. As well as current relationships as well, especially when Constantine was rebooted by DC Comics to be a younger man as part of mainstream DC Comics continuity.
And while this version of him did not make it to his own movie or TV series, when the character joined the TV show DC's Legends of Tomorrow, having a boyfriend became a major and important plot point to the series. But today? In Batman Urban Legends #13 in a story by Vita Ayala, Nikola Čižmešija and Nick Filardi, John Constantine tries his luck further.
Looks like there may be a rematch in the future, once current issues are dealt with.
After all I am reliably informed that once you go Bat, you never go back.
Not like he hasn't come close before, in Batman Damned… but then we all got to see a lot more of Batman in that comic than Constantine ever did.
Also written by Brian Azzarello…
BATMAN URBAN LEGENDS #13 CVR A KIM JACINTO
(W) Various (A) Various (CA) Kim Jacinto
Written by Vita Ayala, Mark Russell, Ram V, and Mohale Mashigo Art by Nikola Cizmesija, Karl Mostert, Anand Radhakrishnan, Trevor Scott, Arist Deyn, and others John Constantine enters the fray to help Batman and Zatanna with their mystical woes, but will he only tear the two further apart? In the final "Eternity" chapter, Christopher Freeman comes face to face with a brutal killer to help solve a decades-old murder…will he survive? Ace the Bat-Hound leads his posse of DC Super-Pets—Merton, Lil' Nutz the thieving squirrel, and Ursa the Russian bear—as they finally break free from the evil lab! But will they get very far without knowing where Batman is held captive? Retail: $7.99 In-Store Date: 03/08/2022