Viewers of EastEnders think mystery newcomer Leo could Frank Butcher's love child Danny Butcher.
Bianca told her daughter their taxi was there and the stranger said to Tiffany: "I'm guessing, your mum?"
Bianca quickly told the man that it was a family wedding and he replied: "That's what I'm here for. Just not yours."
The pair stared at each other before she walked off.
Viewers have been left wondering who he is and some have a theory he could be Frank's son Danny.
In a Digital Spy forum called 'EastEnders reveals Mystery Newcomer Leo' a viewer wrote: "It was revealed last week by Kate Oates and Jon Sen that Bianca's return would kick start a huge story for her loved ones in Walford, setting the stage for 12-18 months of material.
"Tonight a mystery newcomer - Leo - was introduced and seen talking to Tiffany at Callum and Whitney's wedding. Exactly who he is remains to be seen, but Bianca was looking very shifty around him.
"I wonder if this has something to do with the new big story. There's an interesting theory on Walford Web that he could actually be Danny Butcher (the actor is the right age and has a Northern accent) which could potentially kick start a Butcher revival."
Viewers loved the idea of a Butcher revival.
One viewer wrote: "I [bleep] hope so."
A second said: "That was also my first thought. I would genuinely love to see a revived Butcher family with Janine running the Vic."
I know nothing of this Danny person but as soon as I saw him on-screen I thought straight away 'secret son?'
A third wrote: "A Butcher revival, I have championed for many years, It would be the cherry on top to what I think is a very strong EastEnders currently."
Another commented: They're one of the shows classic families. We've had a Slater revival and several Mitchell revivals. It's about time we saw the Butchers make a comeback."
A fifth said: "I did wonder if there was more to his character. Would be great if it was Danny Butcher and the start of a Butcher revival that I've been calling for years!"
Another added: "He's weird. I know nothing of this Danny person but as soon as I saw him on-screen I thought straight away 'secret son?'
Fans of the BBC soap will remember Frank Butcher was on-screen from 1987 till 2o02 and then made an appearance in 2005.
In 1995, while Frank was away from Walford, he met a girl and got her pregnant. She gave birth to his son Danny Butcher, who has never been seen on-screen.
His character left to go to Spain in 2002 and came back to Albert Square in 2005 for his daughter's Janine's trial.
He died in 2008 of throat cancer and his body was brought back to Walford to be cremated.
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