Character Analysis
There's one thing that fantasy isn't, and that's reality. That's why people in fantasy worlds often have objects that would be simply odd in our world. Case in point: Luggage.
Luggage is just that: a chest designed to carry Twoflower's vacation gear. Luggage is made of "sapient pearwood" (1.4.24), though, meaning it's a magical chest that is conscious. It has hundreds of tiny legs beneath it, so it's completely self-mobile, and it's also immune to magic and spells. And it has "lots of big square teeth, white as sycamore, and a pulsating tongue, red as mahogany" (3.8.12) that it uses to remove obstacles from its path by consuming them. And yes, by obstacles, we totally mean people, though we're not sure where they go once chomped.
Unlike the many pieces of luggage lost at airliners and hotels, Luggage will always return to its master. Always. Luggage is the very incarnation of persistence and determination. It will follow Twoflower into the dreaded Temple of Bel-Shamharoth, off the edge of the world, into other dimensions. Although it is not tested as of this novel, it is theorized Luggage will follow its owner all the way to Heaven should Twoflower need "a clean pair of socks in the afterlife" (4.17.3). Perhaps in the sequel…