At work the other night, I was hit by an idea: Why not make it possible for belongings to take the blow in appropriate situations (for instance, your faithful hound knocks you out of a bullet's path and takes it on his flank) and get fallout and traits. Belongings could also possibly start with traits, though I think that I would require them to be purchased from the character's starting trait dice.

This could also be a good way to deal with ships in Star Wars or Firefly games, instead of making the ship a "character" just do it as a belonging with traits to make it interesting.

I'm trying to figure out if there are any downsides to doing this. It seems like it could make belongings much more interesting as time went on, and increase the opportunities to lose your stuff.

I've seen this post/thread for a bit, and finally struck me as to responding -

It's interesting as an idea, but I think primarily as just talking about how flexible the system already is.  This can already be done/is already how some people play, I bet, although not enough of us think about it.  What I mean is that you can take Fallout (or Experience) associated with what happens to your stuff, no reason not to.  Get shot at by a character and take Fallout?  Describe it as "My faithful hound jumps in the way and is shot, bad!"  During the Fallout/Experience application, this can lead to:

"My dog has a limp 1d4"
"My dog has only 3 legs 2d4"
"My dog can take a bullet 1d6"

And so on. 

Spaceship wise, I think you can see analagous ways to do this.

I guess what I'm reacting to is "making it possible" whereas it already is.

If you want to lose a Belonging, that already is an option.  Although, to your point, it doesn't have any association to losing all your other stuff - but you can use additional Experience/Fallout to "buy off " those associated Traits.  Besides, more importantly, mechanically I can't see anyone wanting to lose a Belonging and automatically lose a bunch of Traits and such they've associated with that.  Then again, if someone did, I wouldn't have a problem in a group of consenting to/not vetoing such a call. 

I would not make a ship or such a character - unless it has its own intention and its own ability to define the resolution to Stakes (in which case, of course, it absolutely should be a character).