Emmerdale fans were gobsmacked when Cain Dingle's secret long lost brother Caleb Milligan turned up in the village last year and despite the brothers seemingly sorting out their differences, the Dingle stalwart may be hiding another secret about the new arrival's dark past.
In a flash back episode that aired over Christmas last year, Emmerdale fans discovered Faith Dingle ( Sally Dexter ) had given birth to Caleb (William Ash) in prison and he was subsequently put into care.
Caleb later tracked down his half-brother Cain ( Jeff Hordley ) but the bad boy changed his mind about introducing him to the rest of the Dingle clan resulting in Caleb hitting out and crashing a stolen vehicle.
Cain took the blame for the incident but warned Caleb to stay away from the family, which he did until he was called on to help his nephew Kyle (Huey Quinn).
Despite Caleb helping Kyle, Cain's disdain for his half-brother is evident and Emmerdale fans suspect he may be hiding a secret from their past which may explain why the stalwart continues to hold a grudge against his long lost sibling.
In an Emmerdale Reddit forum, one fan theorised: "Seriously given the circumstances Caleb should be the one holding a grudge against him considering Cain lied to him that his mother was dead thus robbing him of a chance to get to know his family for years and years and since he's been back he's just been helping the family by getting Kyle to own up thus getting Cain out of prison and getting them professional lawyers and yet Cain has this seething hatred for him for honestly no good reason.
"It can't be about the stolen car thing considering he himself chose to take the blame and it was also over 3 decades ago like is there going to be some kinda reveal that something else happened in their past? that we don't know about which explains why he hates Caleb so much?"
The fan questioned whether the Emmerdale stalwart was simply being "unreasonable" or if there was more to the feud.
One viewer suggested Cain suspects his half-brother is "up to something" and the stalwart is a "good judge of character".
"It wouldn't surprise me if at some point it comes out that he met Faith after Cain lied to him and Faith rejected him," they suggested.
However, another fan disagreed and pointed out: "Caleb's actions so far prove that he's just trying to help."
Another fan reasoned: "I think it's about control. Cain has no control over the Kyle situation and he hates not being in control. He hates that Caleb isn't scared of him, and won't be told what to do."
Emmerdale airs on ITV on weekdays at 7pm.