We know very little about Allatar and Pallando, other than that they wore blue,
went East, and fell. It's generally assumed that they chose to set themselves
up as deities or rulers. But it would also be possible that they worked out
some sort of alliance with Sauron, similar to the one that Saruman had in mind.
If Saruman visited them in the East, I wonder how much he would have known
about their particular situations. Perhaps he would have even viewed them as a
valid argument for his own reasoning later on. Something along the lines of
their having a good strategy but making mistakes or being too weak to carry it
out.
Just some wild speculation. I sadly do not own a copy of UT and it's been
awhile since I read it, so I can't recall if there is something there that
would tell against this
theory.
Silverlode
"They looked as he pointed, and before them they could see the stream leaping down to the trough of the valley, and then running on and away into the lower lands, until it was lost in a golden haze."
