Problemas com relacionamentos - laravel (Error: Call to undefined method Illuminate\Database\Query\Builder::mini())

2014_10_29_181650_create_users_fotos_table.php

<?php

use Illuminate\Database\Migrations\Migration;
use Illuminate\Database\Schema\Blueprint;

class CreateUsersFotosTable extends Migration
{

    /**
     * Run the migrations.
     *
     * @return void
     */
    public function up()
    {
        Schema::create('users_fotos', function (Blueprint $table) {
            $table->increments('id');

            $table->integer('user_id')->unsigned();
            $table->foreign('user_id')->references('id')->on('users')->onDelete('cascade');

            $table->string('nome');
            $table->boolean('principal')->nullable();

            $table->timestamps();
        });
    }


    /**
     * Reverse the migrations.
     *
     * @return void
     */
    public function down()
    {
        Schema::drop('users_fotos');
    }

}

funciona.blade.php

<div class="col-md-12">
    <a href="{!! action('CandidatoController@candidato', isset($pessoa->user_id) ? $pessoa->user_id : $pessoa->id) !!}">
        <img src="{!! App\User::primeira_foto($pessoa->id) !!}" class="img-rounded img-responsive" alt=""/>
    </a>
</div>

nao-funciona.blade.php

<div class="col-md-12">
    <a href="{!! action('CandidatoController@candidato', isset($pessoa->user_id) ? $pessoa->user_id : $pessoa->id) !!}">
        <img src="{!! $pessoa->fotos()->mini() !!}" class="img-rounded img-responsive" alt=""/>
    </a>
</div>

User.php

<?php 

// APENAS A PARTE RELEVANTE

   public function fotos()
   {
      return $this->hasMany('\App\UserFoto');
   }

?>

UserFoto.php

<?php namespace App;

use ___;
use Illuminate\Database\Eloquent\Model;

class UserFoto extends Model
{
    protected $fillable = [];

    protected $table = 'users_fotos';

    protected $touches = ['user'];

    public function user()
    {
        return $this->belongsTo('\App\User');
    }

    public function src()
    {
        return ___::cdn_asset("{$this->user_id}/{$this->nome}");
    }

    public function mini()
    {
        return ___::cdn_asset("{$this->user_id}/mini/{$this->nome}");
    }
}