Move to object if collision is triggered

I am trying to make it so when an object with tag "Enemy" enters a collider he gets marked and object with the script on it moves towards it. (Even if the enemy moves and moves out of collider)

Script I have so far:

 #pragma strict
 private var HR : int; //Homing Range
 private var Enemy : boolean;
 
 function Start () {
     Enemy = false;
     HR = PlayerPrefs.GetInt("ECS.Homing");
     GetComponent.< SphereCollider >().radius = HR;
 }
 
 function Update () {
     if (Enemy) {
         //Home In
     }
 }
 
 function OnTriggerEnter (collider:Collider) {
     if (collider.tag == "Enemy") {
         Enemy = true; 
         GetComponent(SphereCollider).enabled = false;  
     }
 }

I'm not sure how to save the single transform of the enemy object that triggered collision and I don't know how to even search for this please help.