How does the Indomitable Soul feat interacts with the Pride domain?

Question

The Indomitable Soul feat (PHB II, p. 80) grants the following benefit:

Benefit: Whenever you make a Will save against a mind-affecting or fear ability, you can roll 2d20 and use the higher of the two die rolls.

Meanwhile, the Pride domain allows rerolling natural 1s:

Whenever you roll a 1 on a saving throw you may immediately reroll the save. You must keep the result of the second roll, even if it results in the roll of another 1.

And it is not clear to me how those two interact:

1. A player rolls two 1s, they are allowed to reroll each 1 (independently), then pick the higher roll.
2. A player rolls two 1s, pick the highest result (a 1...), they are allowed to reroll it, and roll two dies again, picking the highest result.
3. A player rolls two 1s, pick the highest result (a 1...), they are allowed to reroll it, and roll a single die, keeping its result.
4. Something else?

For bonus points, what about the interaction with abilities allowing rerolls on a failed save (not only one a roll of 1). An answer that can manage to cover rerolling generally would be better than one that fixates on the particulars of the Pride domain, though that is the main focus.

Answer 1

With Indomitable Soul, the

Whenever you roll a 1 on a saving throw

condition of the pride domain happens when you roll a 1 on both dice—if you don’t, your roll for the saving throw is the other, higher number, not 1.

And then when the pride domain says

you may immediately reroll the save

you are then

[making] a Will save against a mind-affecting or fear ability,

per Indomitable Soul, so you would roll 2d20 and keep the higher value.

Conclusion: only get to reroll if both dice read 1 (or both dice fail, in the case of things requiring failure rather than 1 specifically), but then you reroll the whole saving throw, which means you roll two dice per Indomitable Soul.

Answer 2

Indomitable Soul isn't a reroll, it's just two rolls. Both of the rolls would be affected by the Pride domain, as they would only be one reroll per die.