Emmerdale fans are sure they've worked out who Caleb really is - and he's not related to Nicky or the Tates.
Viewers of the ITV soap were shown a flashback moment between Cain - played by Jeff Hordley - and his brother Caleb, played by Will Ash, which explained why the pair hadn't spoke for years. Caleb stole a car from the garage that Cain was working at and rather than say it was his brother, Cain vowed to cover for his sibling - but only if he never saw them again.
Later, it was revealed that Cain had lied to Caleb and told him his mother Faith had died a long time again rather than recently.
Faith - played by Sally Dexter - passed away in October last year after a battle with cancer but Caleb was unable to say goodbye, unaware his mother was still alive recently because of Cain's initial lies.
After arriving in the Dales, Caleb has appeared to be nothing but helpful to the family. He even paid for Kyle's legal fees as he confessed to being the one who murdered Al and has formed a close bond with the Dingles.
However, last week, it was confirmed that all isn't what it seems with Caleb.
Caleb and Cain seemed to be getting on swimmingly - but at the end of the episode, he was seen taking a mystery phone call.
"We’re finally making headway," he said to the mysterious person on the other end of the phone, leaving fans shocked as his true motive was finally exposed, "We keep reeling him in until we get exactly what we want."
Now fans of the soap are convinced they've worked out just why Caleb wants revenge on Cain - and it's nothing to do with their 'pact' over the car back when they were younger, and instead something much more recent.
Responding to a tweet about what Caleb's up to, one fan suggested: "Maybe Caleb is Chloe’s Dad. That would also make him Amy’s Dad. This would mean he is Kyle’s Grandad and the reason why he paid for the expensive lawyers.
"This would fit in with him being out to get Cain and Chas for Kyle and Kerry."
One fan loved the theory and penned in response: "My head is spinning from this post lol."
Another viewer penned: " @emmerdale I wonder when Caleb will be busted for not being Cain's brother, but being Amy & Chloë's Dad #Emmerdale," whilst a third wrote: "Is Caleb going to turn out to be Chloe’s jailbird dad???"