Quentyn Martell é o Sol que se ergue no oeste e se põe no leste?

De acordo com a teoria dos fãs que sua namorada está se referindo, sim, Quentyn é o sol que se passa no Oriente.

A profecia de Mirri foi:

"When will he [Drogo] be as he was?" Dany demanded. "When the sun rises in the west and sets in the east," said Mirri Maz Duur, "When the seas go dry and the mountains blow in the wind like leaves. When your womb quickens again, and you bear a living child. Then he will return, and not before."
_{AGOT - Daenerys IX}

Então, para o Drogo retornar:

1. O sol tem que subir no ocidente e se pôr no leste.
2. Os mares precisam secar
3. As montanhas têm que soprar ao vento
4. Daenerys tem que dar à luz uma criança viva

A teoria dos fãs é que a profecia foi cumprida pelas seguintes razões.

Quando o sol nasce no oeste e se põe no leste

De a cidadela :

Consider that Quentyn Martell -- "the Sun's son", referring to the Martell sun -- journeyed from the west to the east, where he died

Quando os mares secam

O mar que secou foi o mar Dothraki. Daenerys notou que a grama do mar de Dothraki havia secado.

De a cidadela :

In Daenerys's last chapter she notes that the Dothraki sea is going dry and the grasses are dying

E também:

Dany set off through the tall grass at a brisk pace. The earth felt warm between her toes. The grass was as tall as she was. It never seemed so high when I was mounted on my silver, riding beside my sun-and-stars at the head of his khalasar. As she walked, she tapped her thigh with the pitmaster's whip. That, and the rags on her back, were all she had taken from Meereen.

Though she walked through a green kingdom, it was not the deep rich green of summer. Even here autumn made its presence felt, and winter would not be far behind. The grass was paler than she remembered, a wan and sickly green on the verge of going yellow. After that would come brown. The grass was dying.
_{ADWD - Daenerys X}

E:

The next morning she woke stiff and sore and aching, with ants crawling on her arms and legs and face. When she realized what they were, she kicked aside the stalks of dry brown grass that had served as her bed and blanket and struggled to her feet.
_{ADWD - Daenerys X}

E montanhas sopram ao vento como folhas

As montanhas que sopram como folhas são a parte complicada.

De a cidadela :

Two of the pyramids of Meereen collapse in smoke and ash following Viserion and Rhaegel rampaging through the city and that she menstruates

Mas a partir de uma teoria dos fãs :

Now the most confusing aspect of the prophesy (my theory for which is kinda tinfoily so bear with me). ‘The mountains blow in the wind like leaves’ does not refer to the destruction of Meeren or any form of volcanic eruption but to Ser Robert Strong. It is widely believed that Ser Robert Strong is Gregor Clegane (aka the mountain)’s reanimated corpse. It is however noted that Gregor's head was shipped to Dorne. This decapitation would mean that the one “mountain” has now become two “mountains”.

Eu gostaria de acrescentar que desde que o corpo de Mountain está em King's Landing e sua cabeça está em Dorne, pode-se dizer que das duas montanhas, uma soprou como folhas para Dorne. Cidadela, no entanto, aponta para a destruição das pirâmides.

Uma visão alternativa é a sugerida por João Duarte nos comentários, se de alguma forma o Muro estiver derrubado, também poderia ser algo parecido com Montanhas soprando no vento como folhas.

OMG SE DANY PODE TER BEBÊS, ENTÃO DROGO VOLTARÁ?

Devemos observar o que a Cidadela diz :

This might be a real prophecy, or it may simply be a sort of curse to strike terror and despair into Daenerys's heart.

E também:

This of course leaves us the need for a living child, and then the "return" of Drogo... though our speculation is that if she has a child, it will be a son that she names Drogo, thereby fulfilling Mirri's claim.

Há também especulações de que Daenerys sangra (Menstruação) pela primeira vez em meses, quando ela está perdida no mar de Dothraki, o que significa que ela pode ter abortado uma criança.

Just past midday she came upon a bush growing by the stream, its twisted limbs covered with hard green berries. Dany squinted at them suspiciously, then plucked one from a branch and nibbled at it. Its flesh was tart and chewy, with a bitter aftertaste that seemed familiar to her. "In the khalasar, they used berries like these to flavor roasts," she decided. Saying it aloud made her more certain of it. Her belly rumbled, and Dany found herself picking berries with both hands and tossing them into her mouth.
_{ADWD - Daenerys X}

E:

When she woke, gasping, her thighs were slick with blood.

For a moment she did not realize what it was. The world had just begun to lighten, and the tall grass rustled softly in the wind. No, please, let me sleep some more. I'm so tired. She tried to burrow back beneath the pile of grass she had torn up when she went to sleep. Some of the stalks felt wet. Had it rained again? She sat up, afraid that she had soiled herself as she slept. When she brought her fingers to her face, she could smell the blood on them. Am I dying? Then she saw the pale crescent moon, floating high above the grass, and it came to her that this was no more than her moon blood.
_{ADWD - Daenerys X}

e

She rubbed her fingers through the dirt, and grabbed a handful of grass to wipe between her legs. The dragon does not weep. She was bleeding, but it was only woman's blood. The moon is still a crescent, though. How can that be? She tried to remember the last time she had bled. The last full moon? The one before? The one before that? No, it cannot have been so long as that. "I am the blood of the dragon," she told the grass, aloud.
_{ADWD - Daenerys X}

Ela não teve uma criança viva, ela aparentemente perdeu o filho. Mas isso mostra que o útero dela pode acelerar .