Trouble accessing a class variable from another class in C#.

Hi, I'm sure this is a simple mistake, but I've looked over several answers here and cannot figure out what I'm doing wrong in terms of properly instancing my GameObject. This is a simple AI script in which I want the NPC to either approach the MainCharacter or Run from the MainCharacter depending on the value of an int in the MainCharacter class, so I'm attempting to access the value in the AI script. Here's the relevant parts of my MainCharacterScript.cs using UnityEngine; using System.Collections;

 public class MainCharacterScript : MonoBehaviour {
     
     public int playercolor;
 
     // Use this for initialization
     void Start () {
     playercolor = 0;
     
     }
     
     // Update is called once per frame
     void Update () {
     
     }
     
     public int GetPlayerColor(){
         return playercolor;
     }
 }

and here's the relevant (and offending) parts of my AIScript.cs:

 using UnityEngine;
 using System.Collections;
 
 public class AIScript : MonoBehaviour {
     
     int playercolor;
     int mycolor = 1;
         float FollowSpeed = 2;
     float FleeSpeed = 8;
         public Transform myTransform;
     public Transform Player;
     private GameObject MC;
     private MainCharacterScript script;
     // Use this for initialization
     void Start () {
         Player = GameObject.FindWithTag("MainCharacter").transform;
         myTransform = transform;
         MC = GameObject.FindWithTag ("MainCharacter");
         script = MC.GetComponent<MainCharacterScript>();
     }
     
     // Update is called once per frame
     void Update () {
             if(Player){
             myTransform.rotation = Quaternion.Slerp(myTransform.rotation,Quaternion.LookRotation(Player.position - myTransform.position), rotationSpeed*Time.deltaTime);
             var dist = Vector3.Distance(Player.position, transform.position);
                // Debug.Log ("Distance to player: " + dist);
             if(dist <= 100){ 
                 playercolor = script.GetPlayerColor();
                 if( playercolor % mycolor == 0 && dist > 10) { FollowPlayer (); }  
                 else if ( playercolor % mycolor == 1) { FleePlayer ();}
                 else {}
             }
         }
  }
     
 }

The problem happens in Update, where I set playercolor = script.GetPlayerColor(); at which point Unity throws a Null exception, as though script was not instanced in the start function. Any ideas / help would be greatly appreciated.