There are a series of deliberate links with the foregoing narrative:
Jerubbaal’s connection with Shechem through his concubine (Judges 9:1; see also Judges 8:31)
references to El/Baal-Berith (Judges 9:4, Judges 9:46; see also Judges 8:33)
the identification of Abimelech’s father as Jerubbaal (Judges 9:1–2, Judges 9:5, Judges 9:16, Judges 9:24, Judges 9:57; see also Judges 6:25–32; Judges 7:1; Judges 8:29, Judges 8:35)
references to the seventy sons of Jerubbaal (Judges 9:2, Judges 9:24; see also Judges 8:30)
references to Ophrah as the home of Jerubbaal (Judges 9:5; see also Judges 8:27)
the role of blood vengeance (Judges 9:24; see also Judges 8:19)
The narrator views the Abimelech narrative as a sequel the Gideon story.1 Abimelech, in his character and actions, to a very great extent recalls his father, whether by similarity or by contrast…. The two accounts are closely related, both thematically and in style and literary structure, and it is in this context that the significance of the account must be sought.
2
1 Now Abimelech the son of Jerubbaal went to Shechem to his mother’s relatives and said to them and to the whole clan of his mother’s family,