“Don’t act like a jackass,” Leech repeated, having swallowed her cereal. “Be polite, try to keep my mouth shut, and definitely don’t try to fuck/suck my way into the job,” she added, staring over at the gargantuan pegasus.

You are asking the impossible.
And you know it.

“Sign, dear, she’s not quite as good as you, no need to be concerned.”
No sooner had the words passed the dickmare’s lips, than Leech reared back and unsheathed the stallionhood from her gullet. “Excuse me?” she blurted, leering up at the adequately hung unicorn.
“It’s nothing against you, Darling, but Sign and I have been friends for ages; don’t be upset that she’s intimately aware of how to press my buttons,” Lilith explained, attempting to calm the harlot.

Leech: "Challenge accepted!"

Through the fog of pleasure, Leech could tell Lilith was close; the throbbing cock was a sure sign, further cemented by the expanding cock-head within her. Magically moving the dickmare’s face to her own, she locked eyes with the pale pony. Summoning the most pleading look she could muster, kissing her host one final time, she took a breath.
“Breed me Sis…”

There is no way Lilith can resist this...