[Monadnock]

Spirits in Shadowrun. In the rules it seems like spirits are called from elsewhere and they have their own lives etc. But there are watcher spirits and Ally spirits. I'm a little fuzzy on watcher spirits but Ally spirits, because they have a formula, they seem like they seem like they are created by the mage. Are they created or does a pre-existing entity with a life and experiences show up if they fulfill the menu points the mage has set out in the formula? Do mages essentially create a magical A.I. or does some entity show up with pre existing conditions and baggage and the mage and spirit are forced to love one another all rapey like, warts and all (providing the GM with plenty of story telling dysfunction to draw upon)?

Man, I gotta add 15 and 15 for the captcha?!?!?!  That's discriminating against orks and trolls!

[Stainless Steel Devil Rat]

The answer is deliberately not given. In-universe, it depends on the point of view of the magician in question.  To an animist like a shaman or a Shinto priest, a spirit is the essence of some thing: the spirit IS the rock, the tree, the stream, the city bus, in spirit form.  To a hermetic, a spirit is elemental energy willed into form and service.  To a Christian theurgist, a spirit s literally an angel from heaven or a demon from hell.  Etc.

[Monadnock]

So depending on the mage's tradition and/or the GM the spirit can have a back story or it cannot?

[Reaver]

So depending on the mage's tradition and/or the GM the spirit can have a back story or it cannot?

Essentially, yes.

Now, is that back story "True"... well no one knows

***
Over the editions, Spirits have changed wildly... so it also depends on the edition - as its the edition that "warps" the Spirit World.

Case in point; From editions 1 - 3 Spirits and Elementals were two separate things, summoned by two different traditions, and behaved in two separate ways.
In late 3e and all of 4e, Universal Magical Theory became the "De-Facto" Theory of magic... And now elementals and spirits got blended into just "spirits".... and the way they are summoned and controlled changed radically...

5e still has UMT as the de-facto Theory, but in later supplements, they opened the door to questioning the UMT, and started to re-introduce some things from previous editions back into the "Spirit World'...

AS to 6e, I do not have the books yet so I can not comment on it's adoption of UMT as the universal theory or not yet. (But given from what I have heard, it sounds like UMT is here to stay, again) 

[Beta]

I don't have the books in front of me, but the impression I have in my head is that the ally spirit is associated with a particular metaplane (it can go there and be called back at will).  But then again how magicians concieve of and experience metaplanes can also vary ...

Anyway, at the very least the formula helps defines how the spirit and our world interact, and may also change the temperament of the spirit? 

But most of all the rule for 'what ally spirits are' should probably be maximum game fun.  In my home game the shaman has always mostly summoned a limited number of named spirits, and after adventuring with one of those spirits on its home metaplane he gained the 'formula' in the form of an item given to him by the spirit as a symbol of the pact between them.  (and the shaman has returned to that metaplane a few times since to help out his ally.  Most recently finding that factions in 'The City' were summoning 'minor' horrors, and having to do something to stop that before the metaplane became corrupted).  For us this approach has been great fun, but for someone else that could be just a distraction from proper shadowrunning?

[Monadnock]

Well, I can think of spirits as being long lived but perhaps without long term memories just a patterned archtype.  There's just so many ways to play them. A spirit could be a drone AI maybe?  Or maybe there are corporate outposts corrupting Earth's Dreamlands?  I was looking for constraints.  I remember shadowrun from the 1 to 3 days so that's I think why I'm a bit lost on this.