Take associated value on lookup column

Hi everyone, 

I have 3lists, the first one, incident with title, priority and category and some others.

The second one is my tracking list, with a lookup value on the title in incident list and others.

The third one, list of my category

In my incident list, priority is a choice column and category lookup column on my category list.

I want to have the priority and category incident associated to the incident title the user choose in my tracking list and I don't want to let the user choose.

Can someone help me ?