赵德芳 / Zhao Defang
Zhao Defang / 赵德芳 is 赵匡胤 / 宋太祖’s son in 170.宋太祖之死：烛影斧声，阴谋论中的人性谜团（下）. He matters most in the immediate palace sequence after Taizu’s death: 宋皇后 reportedly sends 王继恩 to summon Defang, but Wang goes instead to 赵光义 / 宋太宗.
The episode uses that substitution as one of the suspicious details in the succession story. Defang is not shown as an active plotter, but his expected arrival would have supported a son-based succession path rather than the brother-based path that Taizong ultimately took.
Defang’s later sudden death at age twenty-three is paired with 赵德昭’s death as part of the source’s broader 宋初继承合法性危机 reading.