  Not really diverging greatly. We know the ter'angreal is capable of showing past histories, so in some way it's sensible to assume it records data. What I suggest it is then doing is extrapolating out to show a possible future but is unable to take account of its own involvement (or not, as the case may be; this isn't actually necessary). The alternative suggestion is that the ter'angreal is somehow connected to mirror worlds, which there isn't evidence of it doing before - unless you think each of the past histories it has shown has been a minorly divergent mirror, which would be interesting, but as you acknowledge seems like a long shot.  So what we have is a ter'angreal which doesn't have any known interaction with mirror worlds prior to Avi's vision, but has demonstrated an ability to show a possible future in Avi's vision, and may then have deactivated. Aviendha posits that her Talent has altered the ter'angreal in some way, and that may well have happened; there may be a similar example during Egwene's accepted test, since the resonance may have come from her talent as a Dreamer rather than the ring, especially since the ter'angreal showed at least some things that then did come true.  What I would suggest is that it remembers the history of those who have passed through it before, either as a prerequisite of its function or as a side-effect of it. Those memories have to come from somewhere, but on the other hand, it appears that in the world of WOT there is such a thing as genetic memory; see for instance Mat's knowledge of the Old Tongue prior to visiting the Finns, or Perrin's use of it in TEOTW.  Avi's talent then alters the ter'angreal. This actually in some way touches on my idea of the future being altered merely by the act of prophecy, since Avi's talent is to observe the function of the ter'angreal; she may herself have altered it by observing it. As a result of this, it is broken, but not before it malfunctions for a time, by showing Avi a future extrapolated from the data it has already collected.  My intention with the examples wasn't to go outside the world of WOT, as I hope that demonstrates, but to give an understandable example of how I think the ter'angreal is working. If I had wanted to go outside of WOT, I'd have referred to how the Animus works in Assassin's Creed; they're actually really quite similar devices, both taking their information, as it were, from genetic memory.  it is one of the 0 possibilities that Avi changed the ter'angreal.  However, I think it's much more likely that the pillar-ter'angreal always had that function (that being the other possibility I mentioned in my OP)  