Noughts and Crosses Series (2 -5) by Malorie Blackman

Knife Edge:
Two families have been shattered by the divided and violent society they live in. Sephy Hadley – a Cross, supposedly powerful and privileged – has bound herself forever to her nought lover Callum McGregor’s family.

Checkmate:
Sixteen years have passed since Sephy Hadley first met Callum McGregor – and the hate that divided them turned to hope. But the world hasn’t changed quickly enough for their daughter, Callie Rose.

Double Cross:
Tobey wants a better life – for him and for Callie Rose. He wants nothing to do with the violent gangs that rule the world he lives in. But when he’s offered the chance to earn some extra money, how much could it hurt to just this once say ‘yes’?

Crossfire:
Years have passed since the love between Sephy – a Cross – and Callum – a Nought – destroyed their world and changed their families and society forever.Society appears to be very different now. For the first time ever, a Nought Prime Minister – Tobey Durbridge – is in power.