Property does not exist on this collection instance

What I researched might be something related to having 1:N , hasMany > belongsTo relationship, but I do not know what I have to do.

I'm developing a API in Laravel 5.5 and I have some tables that relate when the relationship is 1:1 , it brings the results normally, however, when I have tables the relationship is 1:N , it gives the message: Property does not exist on this collection instance .

Information:

The user table [login_users] is related to the behavior table [behaviors] , 1:N and in [behaviors] only has id .

And the [behaviors] behavior table is related to the behavior code table [lkp_key_behaviors] , 1:1 and [lkp_key_behaviors] , has behavior words such as: Leadership, Organization, etc.

When I change the relationship to 1:1 , hasOne > belongsTo of Models LoginUser and Behavior , brings the results, however of course does not bring all the behaviors, brings only the first.

Model: LoginUser

public function behaviors()
{
    return $this->hasMany('App\Models\Behavior','login_user_id');
}

Model: Behavior

public function loginuser()
{
    return $this->belongsTo('App\Models\LoginUser','login_user_id');
}

public function lkpkeybehavior()
{
    return $this->hasOne('App\Models\LkpKeyBehavior','key_behavior_id');
}

Model: LkpKeyBehavior

public function behaviors()
{
    return $this->belongsTo('App\Models\Behavior','key_behavior_id');
}

Controller: LoginUserController

public function show($id)
{
    $loginuser = $this->loginuser->find($id);
    $behavior = $loginuser->behaviors->lkpkeybehavior;
    $lkpkeybehavior = $behavior->lkpkeybehavior;
    return response()->json(['User Profile' => $loginuser]);                           
}