The Maiar

[Inziladun]

Originally Posted by Sarumian

I would agree with others that Istari did not forget their true self, otherwise how could they stay aware of their mission in ME? But the relevance of their experience could dramatically change with time and Gandalf seems to be the only one capable of retaining his dedication (did the elven Ring help him to some extent?).

The Unfinished Tales essay The Istari indicates that they did indeed remember their true nature while in Middle-earth.

....and though [The Istari] knew whence they came the memory of the Blessed Realm was to them a vision from afar off, for which, (so long as they remained true to their mission) they yearned exceedingly.

It doesn't seem that possession of Narya played a part in Gandalf's faithfulness, though it certainly was an aid. Círdan's words upon surrendering it to him tell of the Ring's power:

'Take now this Ring,' he said; 'for thy labours and thy cares will be heavy, but in all it will support thee and defend thee from weariness. For this is the Ring of Fire, and herewith, maybe, thou shalt rekindle hearts to the valour of old in a world that grows chill.

The Silmarillion Of the Rings of Power and the Third Age

That suggests that Narya's main effect was to arrest weariness, I would say physical and spiritual, that could hamper Gandalf's efforts.

[Sarumian]

Originally Posted by Inziladun

It doesn't seem that possession of Narya played a part in Gandalf's faithfulness, though it certainly was an aid. [...] Narya's main effect was to arrest weariness, I would say physical and spiritual, that could hamper Gandalf's efforts.

That could indeed as it happened to Radagast, which resulted in him abandoning his mission. I think Narya could give some help in this respect.