My theory: Tav is the mortal reincarnation of Amaunator.
Evidence for this comes from the following exchange between two well-known riddle experts:
"An eye in a blue face
Saw an eye in a green face.
‘That eye is like to this eye’
Said the first eye,
‘But in low place
Not in high place.’"
"Sss, sss, my preciousss. Sun on the daisies it means, it does."
This correlation between the daisy and the sun illuminates the whole issue. Daisy keeps talking about Tav's unrealized potential, encouraging them to take their proper place of power and authority, and also keeps trying to establish a closer relationship between them both. But in the end, Daisy is a figure of dreams, a passing, weak thing - like a flower that blooms and fades - while Tav is the waking reality.
I think the conclusion is inescapable. Tav is the embodiment of the sun, struggling to remember their past life and power, the target (of course) of machinations by Shar. "Daisy" is the lowly mirror image held up to point us to this fact.
Also, "Tav" is three letters and "sun" is three letters. Coincidence? I think not!
