Here is a lovely passage from Paradise Lost, Book 9, lines 421-465, in which Satan's innate evil temporarily disappears in the presence of Eve's beauty and goodness. (From this passage, it's easy to see the great influence Milton had on Keats.)

He sought them both, but wish'd his hap might find
EVE separate, he wish'd, but not with hope
Of what so seldom chanc'd, when to his wish,
Beyond his hope, EVE separate he spies,
Veild in a Cloud of Fragrance, where she stood,
Half spi'd, so thick the Roses bushing round
About her glowd, oft stooping to support
Each Flour of slender stalk, whose head though gay
Carnation, Purple, Azure, or spect with Gold,
Hung drooping unsustaind, them she upstaies
Gently with Mirtle band, mindless the while,
Her self, though fairest unsupported Flour,
From her best prop so farr, and storn so nigh.
Neererhe drew, and many a walk travers'd
Of stateliest Covert, Cedar, Pine, or Palme,
Then voluble and bold, now hid, now seen
Among thick-wov'n Arborets and Flours
Imborderd on each Bank, the hand of EVE:
Spot more delicious then those Gardens feign'd
Or of reviv'd ADONIS, or renownd
ALCINOUS, host of old LAERTES Son,
Or that, not Mystic, where the Sapient King
Held dalliance with his faire EGYPTIAN Spouse.
Much hee the Place admir'd, the Person more.
As one who long in populous City pent,
Where Houses thick and Sewers annoy the Aire,
Forth issuing on a Summers Morn, to breathe
Among the pleasant Villages and Farmes
Adjoynd, from each thing met conceaves delight,
The smell of Grain, or tedded Grass, or Kine,
Or Dairie, each rural sight, each rural sound;
If chance with Nymphlike step fair Virgin pass,
What pleasing seemd, for her now pleases more,
She most, and in her look summs all Delight.
Such Pleasure took the Serpent to behold
This Flourie Plat, the sweet recess of EVE
Thus earlie, thus alone; her Heav'nly forme
Angelic, but more soft, and Feminine,
Her graceful Innocence, her every Aire
Of gesture or lest action overawd
His Malice, and with rapine sweet bereav'd
His fierceness of the fierce intent it brought:
That space the Evil one abstracted stood
From his own evil, and for the time remaind
Stupidly good, of enmitie disarm'd,
Of guile, of hate, of envie, of revenge;