Searching a function to get the rotation of one Vector3 in relation to another

with rotations there is actually a difference between Quaternion and Euler Angles. which confuses everyone at first. usually when you are writing code its easiest to deal with Euler angles for calculations if you want simple numbers between 0 and 360.

so most of the time if you just want to know a rotation on an axis you would acually say:

 transform.eulerAngles.x

Quaternion numbers can actually go higher than 360 and lower than 0 but can solve issues of some things like spinning the wrong way to get to a rotation. its kinda weird.

for now I recommend sticking to euler angles in your code whenever you can! its stored as a Vector3

if you are new its very important to know that any time you want Direction between two points you simple subtract the two Vector3 locations and it represents your direction. no need for a function for it. once you have that you can convert to rotation.

   float myx;
     
     //get rotation that makes character look up and down....
     myx=transform.eulerAngles.x;
     print(myx);
 
    //get rotation that makes character look left and right is....
    // transform.eulerAngles.y;
     
     //get rotation that makes character fall over sideways is....
     // transform.eulerAngles.z