The House of Mirth
The central theme of "The House of Mirth" is essentially "the struggle between who we are and what society tells us we should be". Thus, it is considered by many to be as relevant today as it was in 1905. If its sole subject had been the excesses and lives of the rich and famous, by themselves, it is doubtful it would have remained popular for as long as it has. "The House of Mirth" continues to attract readers over a century after its first publication, possibly due to its timeless theme. That the life and death of Lily Bart matters to modern readers suggests that Wharton succeeded in her purpose: to critique "a society so relentlessly materialistic and self-serving that it casually destroys what is most beautiful and blameless within it."
Lydia Hart
After Zoe is released from prison and is found not guilty of Sarah's murder, it is believed that Sarah committed suicide after her diary, found by Mike Barnes (Tony Hirst) is used as evidence in court. Soon Lydia starts to befriend Zoe and she ends up moving in with the Barnes family where Lydia now lives and soon Zoe plans too uncover Lydia's murderous ways as she does not want to be known as a killer. In an interview with entertainment website "Digital Spy", Lister said of the storyline, "It all gets really messy from here! Because Lydia's really deranged, Lydia starts thinking that because she loved Sarah and Sarah loved Zoe, if she gets with Zoe, that'll be the final piece in the puzzle and it'll all work out." 
She explained: "Lydia starts becoming obsessed with Zoe and to keep control, Zoe has to go with it. There's a point where Lydia kisses her! And then Mike walks in and kicks Zoe out."