Johnny will leave this week, just before Christmas, shocking the family with an announcement about his future.
Unsurprisingly his mother Linda is most affected by her son's decision to leave.
But he is of course unaware of the dramatic events that will threaten to rip his family apart on Christmas Day.
Speaking of what Johnny's exit will mean for her character, Kellie Bright, who plays Linda, said: "Because of what has happened with Linda and where she's at in her own story, there is a little bit of her that is relieved because if he is not around she can protect him from the reality of certain things."
But Kellie is confident this isn't the last she'll be seeing of Sam Strike, who plays Johnny.
She said: "I was absolutely devastated and I did say, 'You can't go, I am your mum and I'm saying no!'
"I understand why he wanted to go and I completely support him and love him to pieces. He will very much still be in my life, I don't doubt that. He was at my wedding, for goodness sake."
Johnny's exit scenes will air on BBC One on 23 December at 7.30pm.