arm in arm

adv

1. With arms linked together; with arms around each other's shoulder or waist. (of two or more people)

   “The two friends walked along arm in arm.”

   “Buckingham, doth York intend no harm to us, That thus he marcheth with thee arm in arm?”

2. In collusion, in concert (with someone).

   “‘Frenchmen. Really, I mean to say, Stevens, Frenchmen. […] And to think we have to be seen by the world to be arm in arm with them. One wishes for a good bath at the mere reminder.’”