Revenge of the Dragon Lord

Alien is the humble son-in-law of the Murphy family. He was looked down upon and humiliated by the Murphy members. Only a few knew who Alien is and what is hehind him.
Five years ago, Alien was persecuted by his family and almost died in a foreign land.
Luckily, an elder save him. The elder taught him a lot for two years, and then passed down the position of Dragon Hall Master to him.
The premise was that he had to temper his character by being the son-in-law in Murphy Family for three years…
Now, the test ends and he returns as the dragon lord.