How would i go about drawing a ray from one object to another, obviously the first position will be the ray origin, then I only have to option to choose a direction and not a vector3.
for instance:
Debug.DrawRay(firstObjPos,secondObjPos);
obviously there is no function that allows me to do this atm.
Looking at the docs for Debug.DrawRay, it seems that the first parameter to DrawRay is a position and the second is a delta vector. Given your scenario in your question, it would appear that the following would work:
Debug.DrawRay(firstObjPos, secondObjPos - firstObjPos)
Subtracting the position of the first object from the second object will give a delta vector to be added to firstObject position that will take us to the second object.
Debug.DrawLine does what you need.