Brat Farrar

The story talks about the Ashby family. The parents have dead on a plain 8 years ago and then Patrick (one of the twins) killed his self. 

Then Brat (a boy that looks like Simon, the twin that is alive) impersonates Patrick. The family accepts him but Simon knows that he is not the true twin. 

Then we discover that Patrick did not committed suicide that it was Simon that killed him, he was the murderer of his brother. 

Later Brat killed Simon and he saved his life at the same place Simon killed Patrick. 

We found that Brad its part of the family because he is the son of Walter Ashby, the uncle of the family. 

Finally Bee, the aunt of the family goes to Ireland and Eleanor get married with Brad, they are made for each other.