According to the tiger's own account in the diary, it only gained intelligence and embarked on the path of cultivation after devouring a wounded and dying demon path cultivator in Jiangyou.
The tiger then received the demon path cultivator's legacy and started practicing the Ghost-Controlling Spirit Devouring evil technique.
Later, it was pursued by righteous path cultivators and, by a stroke of luck, escaped to the Cyan Thorn's Ivory Mountain to save its life.
Because practicing the evil technique required blood sacrifices, at an opportune moment, it encountered the Fan family father and son hunting in the mountains, and tasked them with capturing people from outside the mountains.
The events following that are mundane, essentially the tiger's daily grievances and insights into practicing evil techniques.
The diary does not record much about the Fan family father and son with He Xi.
Now that all three are dead, dwelling on it is meaningless.