You have two possibilities:

1. Change your expected result into something more compex, like this:

[
{
'item': {cost: 409, ...},
'likers': [{'id': 1, 'name': 'Brad Pitt'}, {...}, ...]
},
{...next item with likers...}
]

2. You're probably just returning a collection, wich makes a json response like so:

$items = Item::with('likers')->get();
return $items;

Use the Response:json method instead. Pass an array as argument.

$array = array();
foreach(Item::with('likers')->get() as $item){
$itemArray = $item->toArray();
$itemArray['likers'] = $item->likers;//this should work even without toArray
$array[] = $itemArray;
}
Response::json($array);

Be carefull. If all keys in an array are integers, the Response::json result will be an array in json. If there is only one non integer key, the result will be a struct. You handle them differently in javascript.

You can very well use Eloquent relationship for this one.

Assuming you have a relationship likes setup already. Just add this method to your Items model :

public function getUserLikeIdAttribute()
{
    return $this->likers->lists('id');
}

And to get this on your json response, just add this to your Items model :

protected $appends = array('user_like_id');

Now your controller method is as simple as :

public function items()
{
    return Items::with('likes')->take(10)->get(); // Implement the random logic.
}