His mother's brothers spoke of him in the ears of all the men of Shechem all these words: and their hearts inclined to follow Abimelech; for they said, He is our brother.
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).