after a movement, the point will move a proportional amount relative to the location of the point on the diagonal line connecting the y-axis point and the x-axis point.
ASSUME: the point is at the MIDPOINT of the diagonal.
If the initial movement is 2D then
after an initial movement
location of the point (x+d,y-d)
after a 2nd equal movement
location of the point (x+2d, y-2d)
after a 3rd equal movement
location of the point (x+3d, y-3d)
It is linear.
The path is a line.
[As stated, the "diagonal" is increasing in length with each movement.]
Hope that helps.