This reminds me of an experience I had years ago working in a psych hospital. I had started covering a particular unit, along with some others, pretty regularly. I did notice that the staff on this unit did not talk to me unless they had to. I decided they must have had a bad experience with some nurses and just went about my business. After a few months, one of the staff came up to me and said "I guess you noticed we haven't been talking to you. Do you know why?" I said "I figured you were just wondering what ****of a nurse you were getting this time". They laughed. No, it was explained to me that a sometimes-co-worker who had pulled some very crazy, even dangerous "games" at work told them I was her "best" friend. "We thought That's All We Need"...and the they talked and said "You're OK, she probably told you we were her friends." (true)
(btw the troubled coworker did eventually get help, change jobs and became a much more stable person).