Abimelech the son of Jerubbaal went to Shechem to his mother's brothers, and spoke with them, and with all the family of the house of his mother's father, saying,
Evidently Abimelech felt that Gideon’s other sons were ambitious to be king too, though there is no indication in the text that any of them felt this way. He was perhaps projecting his feelings on them, as is often true of ambitious people. They sometimes become paranoid, as Abimelech did (cf. King Saul).