I am exactly 18 minutes into my interview with Neil Hagerty of Royal Trux, when he informs me that I’m wasting my time. Actually, he doesn’t say that I’m wasting my time as such. He tells me that he’s leaving Royal Trux with immediate effect, which, given that Hagerty is one half of Royal Trux, does raise the question of what the point of me flying to the US to interview Royal Trux is. “I’m out of the band,” he nods, when I ask him if I’ve heard him right. “I’m not touring. She steamrollered right over me, man. I’m not … I’m just doing this as a favour to Fat Possum. The album – I didn’t approve of it. I have no idea what it is. I’ve heard like 10 seconds of one song. I’m out, man.”

By “she”, he means Jennifer Herrema, Hagerty’s now apparently ex-partner in Royal Trux (and former wife). The album is White Stuff, the first new Royal Trux studio album since the pair reformed in 2015, which I’m duty bound to point out sounds pretty good: a fittingly wild, strange, angular follow-up to 2000’s Pound for Pound. Fat Possum, meanwhile, is the label that recently signed the duo and which is now, perhaps understandably, engaged in what Hagerty claims is a desperate attempt to try to salvage the band’s reunion, of which this interview forms part. “They’re using this good cop, bad cop shit,” says Hagerty, “like sending you over to stroke my ego, man.”

The way they were … Neil Hagerty and Jennifer Herrema, c.1990s. Photograph: Collexxx-Lex van Rossen/Redferns

It was supposed to be me and her, now it's her and her seven dwarfs Neil Hagerty

He says all this in a tone of amused resignation rather than anger, though he does spend most of our interview lambasting his band’s new album (“She lied and said I approved it and I’ve not even heard it”), his former partner (“She can’t fucking write songs”), the other musicians drafted in (“It was supposed to be me and her, now it’s her and her seven dwarfs”) and their record label (“They’re trying to come clean with it – they think I’m so desperate that I want to be discovered on the next talent show or some bullshit, that I give a fuck about that”).

Nonetheless, Hagerty is remarkably good company – charming, courteous and happy to show me around his adopted home town of Denver – if sometimes given to some curious conversational lurches. At one point, I ask him a question about an old Royal Trux album and somehow end up discussing an episode of The Inspector Linley Mysteries instead.

He’s also occasionally possessed of what you might charitably call a unique take on Royal Trux’s music. I mention the band’s notoriously challenging and impenetrable 1990 album Twin Infinitives – a fragmentary hour of squalling noise, screaming, off-key riffs and out-of-time rhythms that, depending on your perspective, is either a brilliantly confrontational deconstruction of rock music or just the sound of two people completely out of their minds on drugs, or both. And he tells me, straight-faced, that it was heavily influenced by 80s synth pop duo Yazoo. “We loved them. Alison Moyet, man.”

Still, charming company or not, I leave Denver in a fairly agitated state, partly because the band I’ve come to America to interview appear to have split up in front of my eyes, and partly because I’m not entirely sure whether Herrema, who lives in California’s self-styled Surf City, Huntington Beach, knows that Hagerty is no longer in Royal Trux. “I’m not in any détentes,” he says. “I’m not in any discussions with Jennifer.” And I don’t particularly fancy being the bearer of bad tidings to a complete stranger.

When I arrive in California, however, it seems my fears are misplaced. Herrema turns up at my hotel wearing an enormous pair of furry boots, a designer bucket hat and an electronic ankle bracelet: the story of how she ended up under house arrest is so long and convoluted that I quickly lose the thread, but it’s something to do with being pulled over for having a faulty brake light, her driving licence and the sheer number of times she was arrested for drug possession in her youth.

‘I don’t take him seriously at all at this point’ … Royal Trux.

I have blood only 15% of the world's population have. And it's non-terrestrial. I'm human – but how did it get there?

Meeting her after meeting Hagerty, it’s difficult to see how the two ever got on. He is softly spoken, nervous, elliptical and avoids eye contact; she is brash, friendly and greets me with a hug – although you’d certainly characterise both as eccentric. We haven’t been sitting for long before Herrema tells me she recently had a blood test that proved she’s part alien. “I have this blood that only 15% of the world’s population have and they’ve done research on it and it’s non-terrestrial. I mean, like, I’m human – but how did it get there?”

More importantly, she seems blithely unbothered by anything Hagerty has said. “I don’t take him seriously at all at this point,” she shrugs. “He’s done this on every tour. He always shows up, always does the tours. This is just more bullshit. But I’m not bothered by it because it’s nothing bad.” She then offers a litany of complaints about her erstwhile – and who knows, possibly current – partner, which concludes with the memorable line: “He told someone he had control issues. Like, I mean, if you’re talking about me trying to control you not to be a fucking asshole, well, I do my best.”

This is all deeply unexpected, but then again, unexpected and unpredictable was always Royal Trux’s thing. A couple since meeting in their teens in Washington DC, they started making music together in the mid-80s, while Hagerty was a guitarist in Jon Spencer’s pre-Blues Explosion combo Pussy Galore. Although Pussy Galore was a combustible, confrontational, chaotic garage rock band, they sounded like Steely Dan compared to the music Hagerty and Herrema made, something that may have been affected by the fact that the pair were now chronic – and at least initially – unrepentant junkies, their heroin use telegraphed by everything from the label of their eponymous debut album, a photo of the Empire State Building that looked remarkably like a hypodermic syringe, to the turmoil of their sound. “It was a headspace, an alternate reality,” says Herrema. “We were super strung-out. I didn’t think we sounded weird at all.”

Based first in New York then San Francisco, the reality of their day-to-day lives at the time sounds profoundly grim: “Living in a homeless shelter,” recalls Herrema. “Abscesses everywhere. I was like, ‘I’m probably going to be dead before I’m 35.’” But, incredibly, the band thrived. Hagerty and Herrema got clean, the unfathomable racket of Twin Infinitives gave way to a tumultuous, avant-garde take on blues-rock, powered by Hagerty’s astonishingly inventive guitar and Herrema’s attitude-laden yowl.

They made a succession of fantastic albums – Cats and Dogs, Thank You, Accelerator – that lurched between musical styles, from the acoustic blues of Junkie Nurse to the astonishing Stevie (For Steven S), a paean to Steven Seagal that sounded like an 80s AOR band being pushed down a flight of stairs. Indeed, their albums were so fantastic that, even today, they manage to discuss each other’s contributions with genuine respect. Herrema calls Hagerty “a genius” and Hagerty says: “There were always people trying to attack Jennifer, guys trying to tell her what a lead singer should be. But she was great, man.”

They even found themselves caught up in the post-Nirvana gold-rush, signing an eye-popping deal with Virgin, although the label bailed after two albums, perhaps reasoning that its new priority, the Spice Girls, were easier to market than a band who’d just delivered Sweet 16, an album featuring a close-up of a toilet bowl full of puke on the cover. “They literally said, ‘You can’t rollerskate to this’,” says Herrema. “I was like, What year is this? Is anybody rollerskating?’ It was bizarro world.”

Herrema’s kohl-eyed, heavy-fringed look turned her into an unexpected fashion icon. She modelled for Calvin Klein, and Royal Trux proved hugely influential on 00s alt-rock, not least the White Stripes. But by then, they had split up, as a band and as a couple, in suitably dramatic style. Herrema had found out her father was dying of cancer, and dealt with the shock by helping herself to the morphine prescribed to him.

‘We can’t promise anything’ … Hagerty and Herrema on stage in Barcelona in 2017. Photograph: Jordi Vidal/Redferns

A disastrous tour culminated in an intervention, during which Herrema punched Hagerty and Hagerty attempted to have Herrema forcibly committed to a mental hospital. The pair divorced and didn’t speak for 15 years, until a lucrative offer to play a California festival came in. The show was a success, despite the pair declining to rehearse. “We really can’t promise anything,” says Herrema of the band’s famously volatile approach to live shows. “But people are going to get something in real time. They’re not going to get the set we rehearse every night. We’re going to make it difficult on ourselves, and therefore perhaps them.”

The pair’s description of what happened next becomes so contradictory that it’s impossible to work out the truth, although both agree that a subsequent European tour ended in a huge row, some of which took place on stage. Hagerty says relations were strained because Herrema “has a heavy alcohol life”. Herrema says the problem is that Hagerty smokes too much weed. “Sativa. Green crack. He smokes weed and behaves like an insane person.”

Royal Trux’s new album White Stuff.

They regrouped to record White Stuff, but Herrema says Hagerty inexplicably walked out of the sessions, leaving her to finish the album. Hagerty says she wiped parts of recordings, changed songs and didn’t let him hear mixes: “It’s like, urgh, the greatest insult has been done to me.”

Hagerty says he’s out of the band and won’t be taking part in a forthcoming tour. Herrema says he isn’t and he will. Who knows? I leave California bewildered, consoling myself with the thought that, if nothing else, Royal Trux remain as confounding and unique as ever. That’s the only thing about them that seems certain.

• White Stuff by Royal Trux is out now on Fat Possum Records.