почему я вижу undefined, а не true?

function Character() { 
        this.health = 100; 
        this.basicDamage = 10; 
        this.toString = function () { 
            return this.name + this.status; // the properties that I want to reflect 
        } 
    } 
Character.createArcher = function () { 
    var hero = new Character; 
    hero.name = "Legolas"; // set hero name 
    return hero; 
}; 
Character.isAlive = function () { 
    var hp = new Character; 
 if (this.health > 0){ 
     hp.status = true; 
 }else if (this.health <= 0){ 
     hp.status = false; 
 }else { 
     alert("ERROR"); 
 } 
 return hp; 
}; 
var archer = new Character.createArcher(); 
console.log(archer.toString());