Comment by Joyboy on nll

Mirror Legacy is indeed about the legacy and heritage of this family through the guidance of the Mirror. All of the brothers will eventually die, their children will continue their legacy and eventually die as well. With each member dying the Mirror absorbs their cultivation and techniques making the next generation stronger. 

There are 2 protagonists in this Manhwa:
One is the Mirror which is the traditional protagonist but also the passive one most of the time, he can help and direct the family but it will take a long time before he can do stuff on his own.
The second protagonist is actually the Family as a whole, if you remember thir father mentioned a Family poem to be used to name their descendants for each generation, the 4 brothers here are the 1st generation and currently the Light novel is at the 7th generation.

This is a cruel world where proper cultivation was lost when the Mirror was destroyed and all cultivators are "demonic cultivators" to a degree. 
There's a cultivation realm where one needs to sacrifice and absorb 3 other cultivators that have a compatible cultivation method and the youngest brother here is one of them because he will choose one of these culitvations against his master wishes (because the master knows and wants to avoid having another disciple becoming a sacrifice). 
When they are talking about famine destrying the village 20 years ago it was actually cultivators killing mortals but with the tacit approval of this Sect that is supposed to protect them and one of the brothers will sacrifice himself to win the war against the faction of Cultivators that "don't pretend to be orthodox" and want to repeat the slaughter of 20 years ago. 
Finally, the last brother will die from lingering injuries after leading the family for decades because he burnt his foundation to save his son from becoming a sacrifice for another cultivator.