Michael is a good boy.
The light emerald shades of his wings represent courage, while the length, wide as the ocean of the Middle Earth, represents his strength and protection only he alone can offer. Father always says so every time they're alone, except that Gabriel always overhears their conversation through the golden double doors using one of his tricks and Lucifer lurks in the shadows, smirking.
"Es bonum puer, Mikhael,"
Lucifer's fingertips are hot and slick, trailing down the curves of his spines and the thin bones where his wings connect. His muscles flex and stiffen beneath each feather-light caress; sharp nails graze across his skin, digging in before pulling out in cycles, setting the pit of his stomach aflame and his cock throbbing painfully against the suddenly tight materials of his jeans.
"Mae puer, dux praesidium."
Michael is a good boy, Father says, because father does not know that Lucifer slips his hand into Michael's jeans and strokes him hard and firm; thrusting his dick rough and quick into Michael's tight ass until their vessels are completely and utterly spent and bathed in hot sweat and Michael never forgets to erase John Winchester's memories after while Lucifer goes back to the present after erasing Nick's.
Michael is the best, his brothers' think, because they do not know that he has stained and corrupted his grace with lust and greed. None of them thinks that he's fucking Lucifer and he comes like Hell's whore; his mouth hangs open with a breathless sound of 'Lucifer' on the tip of his tongue and a sensual broken moan escapes his lips.
"Sequimurte, nunc et semper, frater."
The thing Lucifer does to him (as Michael to him) is wicked and sinful, but he does not stop because his brothers do not know, nor does his Father.
"Mea, dilectusfilius."
(Or maybe He does, but Michael pretends.)