Bad Bad Boy by Angel Devlin

He’s the bad boy from the wrong side of the river. She’s the rich girl who wants for nothing.
They call them the rats.
The people from the poor side of Richstone river. Privilege lies just a short walk away and Liam Lawson wants it. When the head of Richstone Academy offers four places to the students of Sharrow Manor, he hatches a plan to ensure he and his friends get the opportunity to change their lives for the better… forever. Via a pact of blackmail and corruption of the girls of Richstone.
They call them the riches.
The people from the wealthy side of Richstone river. A life of excess and expectation, but Phoebe Ridley doesn’t want it. When her mother starts a social experiment at Richstone Academy, Phoebe is intrigued to meet the rats, to see how they’ll cope among the elite. She and her friends make up their own experiment. Via a pact of claiming a rat and getting them to do their bidding.
But as the two sides of the river collide and the games begin, the stakes get higher and their moves darker and deadlier… And not everyone will make it out alive.