I thought there were a load of really crappy links between Mark & Grant. How he appeared in London with a leather jacket, comments about him being bald and how he gets it from his dad (the one in America), then the chat with Grant about him being hot headed and he must get that from his mum. It just seemed they were pushing the similarities too much.
I wonder how soon Mark will be back, I wonder if he'll go back to America, ask his mum (Michelle) about it, who will lie to try and keep the secret, which will result in an off screen argument, and him moving to Walford to live. That's when I expect something to happen with Courtney and he'll push her away and have to explain. Then who knows what will happen, Michelle coming over to apologise and reconcile, could that be linked with Courtney demanding the truth from Grant? Anyway purely speculation.