So, there are many stories about the Sun-Maiden (usually called Arien or Urwendi) in Tolkien's legendarium, most of which cohere together pretty well, the most familiar of these being that found in THE SILMARILLION. But from very far back in the legendarium come hints that the sun is in some way diminished or damaged (I'm thinking in particular of the BLT's prophesized Rekindling of the Magic Sun), a point Tolkien stresses in his LETTER TO WALDMAN.*
What strikes me as extraordinary in the Myths Transformed section of MORGOTH'S RING (HME.X.380-381 & 131-132) is that how straightforwardly Tolkien presents Morgoth's rape of Arie, the Maia who ruled the sun, who we are told is "the most ardent and beautiful of all the spirits that had entered into Ea with [Varda]". Tolkien is usually reticent about such matters, but not here:
. . . afire at once with desire and anger, [Melkor] went to Asa
[The Sun] and he spoke to Arie, saying: 'I have chosen thee,
and thou shalt be my spouse, even as Varda is to Manwe,
and together we shall wield all splendour and majesty. Then
the kingship of Arda shall be mine in deed as in right,
and thou shalt be the partner of my glory.'
But Arie rejected Melkor and rebuked him, saying:
'Speak not of right, which thou hast long forgotten.
Neither for thee nor by thee alone was Ea made; and
thou shalt not be King of Arda
. Beware therefore;
for there is in the heart of [Asa] a light in which
thou hast no part, and a fire which will not serve thee.
Put not out thy hand to it. For though thy potency
may destroy it, it will burn thee and thy brightness
will be made dark.'
Melkor did not heed her warning, but cried in his wrath:
'The gift which was withheld I take!' and he ravished Arie
desiring both to abase her
and to take into himself her powers.
Then the spirit of Arie
went up like a flame of anguish and wrath,
and departed for ever
from Arda; and the Sun was bereft
of the Light of Varda, and was stained by the assault of Melkor.
And [the Sun] being for a long while without rule . . . grievous
hurt was done to Arda . . . until with long toil the Valar made
a new order. But even as Arie foretold, Melkor was burned
and his brightness darkened, and he gave no more light,
but light pained him exceedingly
and he hated it.
Nonetheless Melkor would not leave Arda in peace . . .
I think this is unique in Tolkien, the only rape scene in the legendarium
, and I'm surprised more has not been written about it. For a start, it says worlds that it's only the most evil being in the whole subcreation
we are told commits such a deed
. And we are told that it was Melkor's intent to "abase" her.
This scene is also remarkable in that it could be read as the only account on record of deliberate murder by one Vala/Maia of another, Arie being so traumatized that she discorporates and leaves Arda for ever.
There is certainly bride-by-capture, evidenced sinisterly in "Shadow Bride" and light-heartedly in Bombadil's seizing Goldberry, with Eol & Aredhel somewhere in-between (we are told that Aredhel was 'not wholly unwilling'). The most famous such episode, appearing in one of the Great Tales (and thus in a key component part of the legendarium) and prominent within that tale through many iterations, is of course Morgoth's decision to force himself upon Luthien when he sees her dancing in his hall, an act alluded to but not explicitly stated. Luthien saves herself through her spell of sleep. But none of these have the directness and brutality of the Melkor/Sun-Maiden scene.
*[Tolkien's Note:] A marked difference here between these legends and most others is that the Sun is not a divine symbol, but a second-best thing, and the 'light of the Sun' (the world under the sun) become terms for a fallen world, and a dislocated imperfect vision.
--current reading: Raymond Edwards (plugging along), Stephanie Derrick (well into the second section now)