Commentary for Genesis 29:4

ויאמר להם, to the shepherds of the flocks which were laying around in the vicinity of the well.

אחי, an exclamation incorporating a kind of warning, such as אל נא אחי in Genesis 19,8 “please my brothers, do not, etc.!” It is not unusual for people to refer to people close to them or presumed to be close to them as “brothers,” although no biological family ties exist between them at all. Yaakov employed this preamble in order to at once establish a friendly bond between himself and the shepherds.