The singers met on the ninth series of The X Factor in 2012, where Ella finished in sixth place and Christopher went on to bag the third place spot.
Speaking ahead of entering the CBB house, he said: "Ella Henderson rings up and still calls me 'Uncle Chris' because I looked after her on the tour – I was her sort of chaperone throughout the whole of the tour."
He said he's hoping to be an "uncle" figure to some new youngsters in the house. "I'm hoping that I'll be someone that can be the fun one, but also, I like to listen to people and look after them and stuff like that. Like a little uncle."
That being said, he wouldn't say no to someone caring for him in the house. "I hope so! I'm hoping so because my mum and my partner are not going to be around to look after me!"
Chris said he's made no promises to his loved ones about what he'll do or not do on TV, but said: "I think we have an understanding where they're just like 'just be good'. Just be me and don't put on any kind of fakeness or persona. They're looking forward to it. It's going to be something different – new and fresh. Hopefully this will bring out something positive after all the negative stuff with the X Factor."
CBB airs nightly on Channel 5.