First, avoid political struggle.
Li Ji in history did not follow Li Shimin from the beginning as in TV series. Long before the change of Xuanwu Gate, Li Shimin found Li Jing and Li Ji to win their support. However, both of them just declined and made no commitment. Although both of them should be on Li Shimin's side as far as personal relations are concerned, they stand firm. As a general, he can only devote himself to foreign affairs and never participate in internal power struggles. Because of this, after the change of Xuanwu Gate, Li Shimin paid more attention to Excavate and Li Ji.
Second, teach future generations not to participate in power struggles.
In 669 AD, Li Ji's life came to an end. On his deathbed, he told future generations to learn from Fang, Du Ruhui and others. They worked hard all their lives to shine, but they were ruined by their crazy family, and asked future generations not to participate in the power struggle. However, despite the instructions, Li, his grandson, violated his entrustment. After the abolition of Wu Zetian and the establishment of Li Dan as emperor, Li and Luo rebelled. Although Li finally participated in the political struggle, his rule rose up at a critical moment. I'm sure Li Ji would have done the same thing when he was alive.
After Li's defeat, Wu Zetian deprived him of his surname. Later, after the restoration of Zhongzong, his official system was still reburied, and he was also named the ancestral hall by later generations. Li Ji, an outsider, attaches great importance to feelings and righteousness, advances and retreats moderately, and has his own persistence and pursuit. Such a person deserves to be admired by future generations.