Unparalleled Mysterious Son-in-law

*Many years ago, he had been set up by someone.
Inorder to to clear his own name he had been patiently waiting for many years and helped the Country eliminate the traitor for his own good.
After his success, he left. For fulfilling his grandfather's promise, he had to lower himself to become the son-in-law of a small family. 
What he got in return was the scolding and criticism of the family. 
As the hero who Hiding his own identity, how was he going to turn the tables?