how to say Relationship chemistry I know there is a word to describe "relationship chemistry" in Chinese. I think it's a 2-character word. Sort of like Extrasensory perception (ESP).

How would you say this?
靈犀?

http://dict.revised.moe.edu.tw/cgi-bin/cbdic/gsweb.cgi?o=dcbdic&amp;searchid=Z00000065618

心有靈犀一點通

or, in the past, 紅線 + 月下老人

http://dict.revised.moe.edu.tw/cgi-bin/cbdic/gsweb.cgi?o=dcbdic&amp;searchid=Z00000087005

http://dict.revised.moe.edu.tw/cgi-bin/cbdic/gsweb.cgi?o=dcbdic&amp;searchid=Z00000164586

info added.

one character? then it must be 緣, which could be translated to fate, destiny, or serendipity.

http://dict.revised.moe.edu.tw/cgi-bin/cbdic/gsweb.cgi?o=dcbdic&amp;searchid=W00000011822

the fourth explanation:

人與人或事物之間遇合的機會


"有緣" is the simplest usage