I was a bit disappointed with this tbh.
Everyone was so extremely flawed, except Viv and Leila.
I suspected it was Mary doing it all along, but we never really found out if it was all down to her; she was creepy as hell though.
However, Mark also wasn't truely how he presented himself, lots of questions hanging there. So I suspect it was a combination of Mark and Mary, sort of pulling Viv between them; and the children as well, everyone wanted a piece of Viv.
So many questions unanswered that I wonder if the makers are hoping to revisit this in the future.
Too many attempts at twists and turns, in what was really a rather weak plot - one of which was Mark being the one ending up in hospital when, I suspect, the viewer was suppose to think it would be Viv, not that much of a surprise or twist. The writers clearly thought we'd all be on the edge of our seats, given the way they dragged it out until the very end.
One thing that did stick out as a clumsy way of mucking things up for Jake was Leila walking in on him and Stella, post their supposidly last sexual encounter.
At what point would he have given her a key to the flat? Why would she need one? And given that he and Stella were regularly having sex there, why on earth would he take the risk that she might walk in on them; very silly bit of sub plotting.
Having said that, I did enjoy it as a bit of 'not having to think' entertainment and would probably watch any further epitsodes.