"I really rather owe you an apology," you say, "for I've called you here under rather false pretenses." You loosen your collar rather hastily.
The young blonde pulls away, looking up into your eyes with apprehension. "Professor, I… "
"Oh, heavens, no, no," you tell her. "I would never dream of- well, I would hate to give you the wrong idea." Your words of reassurance buy little, as your pallor continues to rapidly dwindle, sweat running from every pore, the flush of your face fading to jaundice with a greenish tinge; the skin of your mouth sucking visibly inward with your increasingly strained breaths.
"Professor?" she says.
You double over, hand clutched to your breast, but keep your eyes aligned with hers. Trying, and failing, to keep your voice even, you say, "I must admit to having enjoyed being your professor, far too much so in fact. It's caused me to overstay my welcome, as it were. "
"I don't understand. Do you need a doctor?"
"No," you insist, still straining to keep your tone dissonantly cheery. "There's nothing that lot could do for one in my condition in any case. I have been… self-reliant for quite some time."
She gasps as you feel the burning in your eyes coming to a head, vessels bursting, a trickle of blood streaking down your gaunt face. The pain is palpable now, impossible to suppress. The moment is near, so you suppose it's time to end the charade and make plain the way of things.
"I owe you a degree of explanation," you say, rising, "or perhaps simply a demonstration."
"Professor..." She is halfway across the room, her stance at desperate odds between coming to the aid of the dear, suddenly feeble man she knows you as, and sensibly bolting from the room. You can appreciate both her sentimentality and animal's instinct of survival, but the longer she remains in the paralysis of choice, the more your predatory aspect comes alight, eager to prey on her indecision.
You straighten as much as you are able, "You were always so attentive, my dear. So keen witted, kind hearted, but most critically, oh so very infused with the essence of life itself, utterly vital." Even now, you study her form, as she begins to cower, her youthful beauty, her slender and petite enviable silhouette.
You spread your collar further, tearing the shirt now, to reveal your chest, where the skin, too thin and discolored with bruised blotches, is roiling with misshapen lumps pressing out from within.
She recoils, as you place your fingers about your collarbone and press into the pliant flesh, blood oozing from the puncture like the filling of a pie. It hurts, but you must show her, make her see, understand what you are.
With a viscous, leathery squelch, you peel back the flap of skin of your torso like a curtain, holding it out as if it were the wing of a dinner jacket. She screams, naturally, as your grisly gallery of innards is revealed, at your several hearts still surging lifeblood through your tissue, at the barely identifiable abomination of anatomy within your cavity, at the disparate organs you've collected as piecemeal replacements to extend your span within the identity of the meek Professor.
You knew it was foolish to go so long with mere maintenance, harvesting a mismatch of kidney, bone, blood and sinew to renew yourself as opportunity allowed. You are more than overdue for a complete renewal, replacing your taxed, withered and blackened composition from root to stem with something new, fresh, vital.