when two light rays intersect in any medium why dont they deviate from their line of path?

It dependent on wich light are you talking about(there are a lot…)

But if you talking about visible light, as I assume, it depends from the color.

If two light with the same color and same property meet each other,then are that get light will increase and the intensity will increase a little bit(the visible part)

If there are 2 different light, it will happen the same as above but the 2 colors will mix together, making different combination of it in a different part of the area.(in some area will be dark,some lighter, some more saturated,some more insaturated)