Let us pause for moment and consider hip-hop’s supporting characters, its second-stringers, the doughty lieutenants of rap. Their story is always the same: hoisted to a weird kind of semi-fame by the best-known member of their crew’s success, they launch their own solo career, but it never quite takes off in the same way as their more celebrated mate, and obscurity beckons. Such was the fate of Jim Jones of Cam’ron’s Diplomats, AZ of Nas’s the Firm, Gunplay – the member of Rick Ross’s Triple Cs who distinguished himself by getting a big swastika tattooed on his neck, apparently symbolic of his desire to “Nazi that shit … put all the fake motherfuckers in the gas chamber” – and Sheek Louch and Styles P of Jadakiss’s the LOX. It’s what befell Big Syke, once of Tupac’s Thug Life and Outlawz, his career possibly hampered by his decision to change his name to Mussolini. And Lloyd Banks, the member of 50 Cent’s G-Unit crew who had to be partially nationalised by the British government during the 2008 liquidity crisis.

You do wonder if their names haunt Darold Ferguson Jr, currently plying his trade as A$AP Ferg, the second most famous member of A$AP Mob after A$AP Rocky. The latter has had two consecutive No 1 albums in the US; by contrast, Ferg’s uneven debut, Trap Lord, was the 74th bestselling hip-hop album of 2013. There’s certainly a sense of urgency about the way Ferg is talking up its successor: “You might not get another album like this from me.” A certain seriousness pervaded a listening party in New York, at which the rapper demanded the bartenders remove everyone’s drinks before playing a track called Beautiful People, in order that his audience might concentrate harder on its post-Black Lives Matter message of empowerment. He has compared another track, Strive, to “Picasso taking a risk when he decided to go abstract”, which might be pitching it a bit high: it turns out to be a commercial pop-house track, albeit one featuring a guest verse from Missy Elliot and a lovely, understated piano line pinched from Alicia Myers’ oft-sampled disco-gospel hit I Want to Thank You.

Still, the presence of a pop-house track tells you something about the difference between Always Strive and Prosper and A$AP Ferg’s debut. There was a lot to admire about Trap Lord – the way his delivery combined agility and real charm with a slight hint of bug-eyed insanity; the brilliant single Shabba in particular – but its sound and subject matter became a bit monotonal: clearly keen to put some artistic distance between his debut and A$AP Rocky’s, it held pretty fast to a kind of stark darkness. Always Strive and Prosper takes things to the other extreme. There are tracks that stick with Trap Lord’s austere blueprint, not least the Rick Ross collaboration Swipe Life, but they’re scattered among a plethora of different musical approaches. Beautiful People’s hallucinogenic early-70s soul turns up alongside sonic experimentation (the fractured, weird Uzi Gang; World Is Mine’s clouds of ambient synth); Grandma’s curious but effective cocktail of echoing voices and proggy synth arpeggios shares space with the breezy, cliche-free pop of Let You Go, a track that gamely suggests that Ferg’s girlfriend slinging her hook because she was sick of him luridly detailing their sex life in his lyrics demonstrates his noble willingness to sacrifice everything for his art.

Not everything works – there’s something a bit wan about the gloopy R&B of I Love You, and Yammy Gang doesn’t feel minimal so much as half-finished – and at least one of the ideas on offer seems strangely familiar. Skrillex turns up on Hungry Ham, as he did on A$AP Rocky’s hit Wild for the Night, although it’s hard not to think Ferg might have got the better deal. Skrillex’s collaboration with Rocky came at the height of his fame as a megastar provider of subtlety-free EDM: cue three minutes of teeth-gritting dayglo synth screeching. Since then he has reinvented himself as a more complex and refined figure – capable of working with Diplo and Four Tet alike – and his production here follows suit: menacing swarms of electronics cloud the middle distance while vocalist Crystal Caines delivers the hook in a childlike voice. The overall effect is impressively chilling.

There’s a chance that all this could sound like a man wildly chucking ideas around in the hope that one sticks; that it feels appealingly eclectic rather than desperate is down to Ferg himself. His lyrics have abandoned the more knuckle-brained excesses of Trap Lord – mercifully, there’s no equivalent of Dump Dump’s grim stew of machismo, misogyny and curious threats about sticking MDMA up your bum – in favour of the kind of clearly drawn pen portrait of life in Harlem’s Hamilton Heights found on his debut’s closing track, Cocaine Castle. The best lyrics here are blessed by the presence of his Uncle Psycho, last spotted receiving a pretty thorough enumeration of his personality flaws on Uncle, from the 2014 mixtape Ferg Forever: no spoilers, but the nickname clearly wasn’t intended as an ironic commentary on his workaday life in admin. On Psycho and Let It Bang, Ferg flips seamlessly from wry detachment – retelling his relative’s excesses as gags – to something darker and more impassioned: the combination of amusement, affection and horror-struck frustration feels realistic and affecting.

There’s a certain irony about the fact that the world he describes so vividly is apparently vanishing. According to the New York Times, Hamilton Heights is being rapidly gentrified, an expansion of Columbia University drawing in new residents you can’t imagine being too thrilled at having good old Uncle Psycho for a neighbour. Whether A$AP Ferg is also going up in the world is an intriguing question. As he’s glumly noted himself, hip-hop history suggests not: “The first person comes out and … you really hardly see the next person blow up.” He may yet be condemned to the time-honoured role of doughty lieutenant, but Always Strive and Prosper – eclectic, smart, skilful, occasionally experimental – is strong evidence that it would be a terrible oversight.