As with most places of employment that I have worked at, I have ended up with two individuals whom surpass the role of coworker and have become friends.
The mechanics of this likely remain the same in the modern era, although much more delicate than they used to be.
In one case it is a someone who used to report to me (I hired them originally) who was my "therapist" in my senior management role, the one who I could go to when I was frustrated or upset or just "out of sorts" and knew both that everything was confidential and that the advice I was getting was good. The second is a more recent addition, a coworker in my area who, as we worked together, found out we had more in common as people than just we both worked in the same department.
I say "more delicate". There is almost a dance that happens now, a slow unveiling of the personality, as one continues down this path. One will have a brief burst of personality in a small, trivial way - what is the reaction? Is it responded to? Is it positive? Is it ignored? Or one is the recipient of such a contact - the same sorts of questions arise: Should I respond? Have I mis-interpreted the comment? Layer by layer these contacts continue until inevitably there is a conversation - always between the two parties - where something truly personal is revealed.
And suddenly, you find out you have lots of things to talk about.
It strikes me as odd that these sorts of relationships now in the workplace are what I feel as if the French Resistance must have been like in World War II: heads down and not attracting attention to yourself, briefly seeing your comrades in the daylight without acknowledging them, and clandestine meetings where real matters are discussed. There is thought given to what is said on private and non-private communication lines.
At some point, of course, all of this end: I will leave, or my likely my friends will leave. The interesting thing to me (if such a thing can be interesting) is that when they leave, there likely will not be anyone to take their place - much like in the Resistance when people disappeared, they did not come back. Which makes me equally happy and sad, of course: happy for my friends, selfishly sad for myself.
When I had started work all those years ago, it seemed like almost everyone I worked with was a work friend. Now, entering what seems like it could be end of the process, I find it quite reversed: the friends are few and far between, the silence defeaning.