Warning: This article contains spoilers for You season 4, part 1.
You season 4, episode 5 reveals the identity of the Eat The Rich killer - a move both shocking in how it is revealed earlier than many may have been suspecting it would be, and in how it sets up the second half of the season. You has primarily been about Joe's own serial stalking and killing tendencies, which makes the move to focusing on another killer entirely something of a plot twist. Indeed, online speculation contained a considerable amount of theories that the killer and Joe's stalker may have been Joe himself as a result, or otherwise someone who'd he previously hurt. However, this ended up not being the case.
You season 4, part 1 closes with Rhys revealing himself to be the Eat The Rich killer, attempting to first align himself with and then try to kill Joe. Their confrontation ends with Joe narrowly escaping burning to death, and returning home only to see Rhys officially announce his mayoral candidacy with language that makes it clear he will kill again. In doing so, Rhys answers some of You season 4's biggest questions, raises others, and sets up a fascinating premise for You season 4, part 2.
Why Rhys Killed His Friends In You Season 4
Rhys' confrontation with Joe has him call Roald - and by extension the rest of the rich group Rhys had been established as having hung out with for some time - a "spoiled violent little sh*t". While Rhys is depicted as violent himself, he isn't exactly wrong in his description of his colleagues. You season 4 dedicates a not insubstantial portion of time to showing how awfully the clique Joe finds himself in treat others - especially those they deem as lesser than them. Combined with his speech that he wishes to become mayor of London for "change brought on by someone who truly sees" the struggles of the working class, Rhys' motivation is relatively clear.
However, it seems Rhys is similar to Joe, in that his motivations are somewhat a facade to allow him to enjoy his depraved hobbies while still considering himself a moral person. When Rhys texts Joe about killing, it's clear he takes personal pleasure in doing so throughout his time in Netflix's You plot, and while that likely is in part because of the misdeeds he's seen his peers do, this doesn't seem to explain it by itself. This may present a chance for Joe to truly see his own motivations for killing or stalking someone, instead of the justifications he often used.
Why Rhys' Killer Plans Involved Joe
Perhaps one of the most surprising twists of You season 4 part 1 is not the reveal that Rhys is the killer, but that he has been stalking Joe with the intention of recruiting him to his cause. It's clear from the offset that Joe considers himself and Rhys like-minded peers in a sea of rich elite who have only known wealth. However, logically, Rhys' seeming reciprocation of this feeling looks for a moment to have potentially been platitudes he used in order to lower Joe's guard when it is revealed he is the You season 4 killer.
This is quickly reversed when Rhys explains he's been following Joe's serial killer work for some time, and wishes to channel his abilities into a murderous collaboration. Notably, Rhys mentions how Joe has been able to "escape scrutiny" and praises him for his ability to do so, suggesting that this offer is because of Joe's consistent escapes from even the most unlikely of circumstances. That said, the You season 4 killer also states "in light of what's worked so well for you in times past, it seems my best option that doesn't involve on luck involves framing a dead person," which suggests Rhys believes some of Joe's escapes have been luck-based. This would explain why he's willing to reveal his secrets to Joe really - because he believes he can outsmart Joe if needs be.
The Biggest Clues To Rhys Being You Season 4's Killer
Rhys did have several large hints to him being the You season 4 killer right from his introduction. However, these were easy to miss, as every character introduced at the start of season 4 is pretty suspicious, and before the bodies start piling up it does seem like any of them could end up being the antagonist of the plot. Indeed, one of the most suspicious things about Rhys is that he isn't an unhinged socialite who has been wealthy since his birth - and this discrepancy provides him a stronger motivation than any of the petty squabbles between the rest of the cast.
Rhys makes his distrust of those who've grown up with immense wealth clear from the offset, and then reveals shortly after in the plot that he has lied within his famous book. This is specifically about his time in jail, which establishes him as capable of successfully hiding major details about his life early on in Netflix's You show plot. Rhys is also the only person in the bar when Joe goes back after seemingly killing Malcom, despite explicitly talking about his busy schedule, suggesting he's there because he knows Joe will return.
Though Rhys being absent from the countryside retreat in You season 4, part 1 may have suggested to some that he couldn't be the killer, it actively makes the opposite true. The inhabitants of the manor quickly dissolve into very clearly cruel behavior quickly enough that it demonstrates a complete lack of impulse control, which is at odds with the methodical tactics of Joe's stalker and the killer. Similarly, Kate is also made into a less likely candidate due to how following this avenue would be too close to the most recent plot with Love - which makes Rhys the most likely candidate by his omission.
What Rhys Being The Killer Means For You Season 4, Part 2
The way Rhys is set up as the killer establishes that You season 4, part 2 will be a cat and mouse game between Joe and Rhys. Part 1 ends with Joe actively rejecting the subject of his most recent obsessive fantasies in lieu of trying to stop Rhys, strongly suggesting his primary focus will be to stop the Eat The Rich killer in the second half of the season. You season 4, part 2 taking on this story would be a fresh approach for the show, flipping the script by having Joe seek redemption by instead taking down someone who operates almost identically to how he historically has in the series.