actual_model.js

ActualModel = ModelBase.extend({
  related: function() {this.hasOne(OtherModel);}
});

model_base.js

ModelBase = Model.extend({
  hasOne: function(Model, fkey) {
    Model.prototype.hasOne.call(this, Model, 'myconstantforeignkey')
  }
});

plugin.js

_.each(['hasMany', 'hasOne', 'belongsToMany', 'morphOne', 'morphMany', 'belongsTo', 'through'], function(method) {
  var original = Model.prototype[method]
  Model.prototype[method] = function() {
    // Stuff here
    return original.apply(this, ...)
  };
});

As far-fetched as this example is, it is technically broken