A familiar passenger can become reassuring company without ever becoming a friend.

Recognition does a surprising amount on its own. The same person on the same carriage every morning becomes a fixed point in the day, and their presence quietly confirms that things are running normally and you are where you should be. No names are exchanged, no conversation happens, and something real is nonetheless provided.

If you commute, notice who you would miss if they stopped appearing. A nod is enough, and it does not have to become anything more. Not every useful connection needs to be developed, and some of them work precisely because they never are.