Given a string of text (clear, or cipher), you could work through it character-by-character and produce two-character co-ordinates from each adjacent pair. So, for “the quick brown fox…”, your first co-ordinate is (t, h), the second is (h, e) and so on. If you plot these co-ordinates, and the lines between, on an X Y grid, with the full character set on each axis, you’ll get a two-dimensional pattern of points and lines representing adjacent characters. With sufficient text, and a bit of work, you could emphasize strong relationships. I’m guessing natural language and some ciphertext will have distinctive and different characteristics. Is this pattern “a thing” in maths and if it is, what is the pattern of relationships called? I’d guess a map(?) of nodes(?) and links(?).