Help, please.

[dumbledore11214]

Hi, guys! I know that the question I am about to ask will be rather 
difficult and if nobody can answer, I understand. :)


But I am pretty sure that the book, I am trying to remember was 
mentioned here, that is why I am trying. 

At the end of the story, two protagonists merge in one, by that act 
the soul of the evil one is saved.

Can anybody identify this book for me?


Thanks a lot and sorry that I cannot offer any more clues.


Alla