You need to learn this:

http://laravel.com/docs/5.1/eloquent-relationships#many-to-many

Just work through it and it should make sense. You need a pivot table for many to many.

Mick

Hi phpMick,

thank you for your answer.

Here is what I have:

app/User.php

class User extends Model implements AuthenticatableContract,
                                    AuthorizableContract,
                                    CanResetPasswordContract
{
    use Authenticatable, Authorizable, CanResetPassword;

    /**
     * The database table used by the model.
     *
     * @var string
     */
    protected $table = 'users';

    /**
     * The attributes that are mass assignable.
     *
     * @var array
     */
    protected $fillable = ['name', 'email', 'password'];

    /**
     * The attributes excluded from the model's JSON form.
     *
     * @var array
     */
    protected $hidden = ['password', 'remember_token'];

    public function bonds()
    {
        return $this->belongsToMany(Bond::class);
    }
}

app/Bond.php

class Bond extends Model
{
    protected $fillable = ['description', 'amount', 'debtor_id', 'creditor_id'];

    public function debtor()
    {
        return $this->belongsToMany(User::class, 'bond_user', 'debtor_id', 'user_id');
    }

    public function creditor()
    {
        return $this->belongsToMany(User::class, 'bond_user', 'creditor_id', 'user_id');
    }

}

two new migrations:

public function up()
    {
        Schema::create('bonds', function (Blueprint $table) {
            $table->increments('id');
            $table->text('description');
            $table->float('amount', 8, 2);
            $table->integer('debtor_id');
            $table->integer('creditor_id');
            $table->timestamps();
        });
    }

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

----------------------

public function up()
    {
        Schema::create('bond_user', function (Blueprint $table) {
            $table->increments('id');
            $table->integer('user_id');
            $table->integer('debtor_id');
            $table->integer('creditor_id');
            $table->timestamps();
        });
    }

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

I can save a debtor_id and creditor_id if I create a bond. But if I try to get the User from $bond->debtor, I get an integer only.