Aisin-Gioro Yin Zhen is the 4th Prince of Emperor Kang Xi and Grand Imperial Concubine De. He has another blood brother, Aisin-Gioro Yin Ti (14th Prince). However, in the famous princes' fight for the throne, Yin Zhen was part of a different faction from his blood brother.
Yin Zhen, along with Aisin-Gioro Yin Xiang (13th Prince), initially supported the Crown Prince for the throne succession fight but after the Crown Prince was deposed by Emperor Kang Xi for the 2nd time and no successor was named, and after Aisin-Gioro Yin Si (8th Prince)'s faction started to make their move and targeted him, he decided to enter the succession fight for himself.
(Source: MusicalVeggies at kisskh)
