Ben works for his father, as this goes on you will see that out of the family, it is Ben that manages and protects the families money, invests, and ensures solvency. He is the one that says yes/no to expenses etc. A role his entire family appreciates from him.
The Matty issue has not gone away, it is still very much in the forefront of Riley's mind. Riley is trying to survive this situation and has very few options. So Riley does what Riley has always done, found a way to worm his way into affections.
As for Ben, we're starting to see him differently, seeing inside his head will change perspectives. For example we have learned that his job at Harrison's from the last book was only a way to get to Kier. It was Ben who paid for the lawyer and not Kier's father. All so he could find, and attempt his experiment. I don't think he set out to choose Kieran, but circumstances of Kieran's assault put him squarely into Ben's crosshairs.