Voldemort sat comfortably in his armchair in front of the fireplace in the Riddle Mansion, contemplating the dancing flames, when he heard a slithering noise coming from the doorway. Nagini was returning from her hunt.
"Found anything?", he asked her in parseltongue, and turned the armchair around with difficulty. He was still trapped in that ridiculously small body that was as yet the only thing in the way of a physical form he had been able to achieve.
Nagini understood, and wound her long, taut, scaly body around to spare him the effort. "No prey today", she hissed sadly.
Voldemort stared back at her with an emphatic expression. "And still no dead Harry Potter today", he replied equally full of grief.
"Then perhaps we should find comfort in each other", the giant snake suggested, wriggling her tail seductively.
"That is a remarkably good idea". The Dark Lord turned around on his belly and presented his infantile butt to Nagini. "I want to feel you inside of me."
The humongous snake complied, hissing pleasurably, and, lacking a penis, stuck the very similarly shaped, though scaly, end of her tail into Voldemort's asshole and began fucking him with deep thrusts. The Dark Lord groaned. "Deeper, deeper!" And they fucked till all his internal organs had been penetrated.