On tonight's show, some of the housemates sit in the garden and discuss the growing relationship between Christopher and Mark.
Later Mark says that he would like to go on a picnic with Christopher or Christmas as he is increasingly known.
Mark then goes to the Diary Room to talk about his friendship with Christopher, telling Big Brother: "It’s evolving."
He also says that they have got a lot closer and that Christopher is an amazing person.
But Mark thinks it’s disrespectful to Christopher to call him the new Matthew, Mark says: "He’s not the new Matthew, he’s just Christopher."
In the evening, and after being provided with booze, Mark then has some time out alone in the Store Room before inviting Christopher in where the pair seem to kiss out of sight from the cameras.
Come night time, Christopher and Mark are in bed together and there's little doubt about what the pair are up to.
They go under the covers and kiss: One can be heard whispering that they shouldn’t be kissing.
There is some more movement under the covers and kissing noises before both appear above the covers.
Mark rolls over and goes to sleep and Christopher stares at the ceiling.
Big Brother airs tonight at 9PM on Channel 5.
Browse pictures of tonight's show below...