While most of New York was dead to the world- sleeping soundly under the serene 1 AM moonlight, there was one area of the city in particular that was completely alive and bursting with action.

The girl with unruly chestnut curls whipped around, plunging a blazing seraph blade into the revolting flesh of demon facing her, black blood spraying and sizzling on her indestructible shadowhunter gear. Pure adrenaline was rushing through her veins, and in her head, the voice of fear was completely silent; she was a shadowhunter, and this is what she was born to do. The ruby suspended on a chain around her neck pulsed repeatedly, warning of oncoming demon presence, and just as that creature had been banished back to whatever hell it'd come from, another appeared behind her screeching an unearthly screech. Her also fearless Parabatai was on it in a second, instantly covering her back, like she had many times before in battle, and in life in general.

These were only lesser demons, which were usually a breeze to destroy, but there was a whole hoard of them in an enclosed space, making them a pain in the ass to dispose of: as soon as you'd gotten rid of one, another one would appear seemingly out of nowhere and attack you from a different angle, leaving no time to pause in between. Not that she needed to pause, obviously.

As she was pounced on by yet another demon, she noticed her partner hurl a dagger at one demon while stabbing at another simultaneously with a long blade. The dagger sailed soundly across the alleyway that they were battling in and embedded itself right in the centre of the beast's chest. The demon flailed angrily, hissing like an enormous cobra as it did so, and spat venom from its deadly mouth as it did so. She heard her Parabatai curse loudly and dodge out of the way as some of the venom spattered onto her forearm, before finishing off the creature that she was directly battling with a swipe of her blade.

The girl slashed at a nearby demon with her electrum whip, severing its ferocious head with a single flick of the wrist. Her ruby pendant stopped pulsing shortly after. She observed the alley briefly, checking for any other signs of hellish life, and, after determining it clear, she headed over to check on her Parabatai, who was using her stele to draw an iratze on the patch where the inchor had splashed on an exposed patch on her arm.

"That's the last of them," her partner said, finishing the rune with a curve of the stele and giving her a grin. Her partner may look delicate on the outside- she was small and slender with hazel eyes that twinkled as the 2 AM moonlight reflected in them and her dyed chocolate hair was streaked with a golden blond in places where her natural colour shone through, but anyone who knew her and her heritage knew that she was just as strong as any man, perhaps stronger. This didn't stop many guys from gazing after her though, which she often used to her advantage. "Not too bad, Lightwood."

The girl grinned back, pulling her hair out of its messy fighting braid and letting her curls loose on her shoulders. "Same back to you, Herondale." She leaned back against the wall next to her sworn sister, and gazed up at the stars. Unlike her partner, she had dark chocolate eyes and wild, untameable hair that barely stayed where it was put for 5 minutes at a time, proving to be rather difficult during fights. She knew for a fact that she got it from her father, just like most of her looks. It was at times like this where she was jealous of her mother, who had long black hair that could be slicked right back and would stay there for hours.

"Well," said her partner, moving away from the wall and sheathing her blades, "I bid you goodnight my sister, and I'll meet you back at the Institute usual time, unless my work prevents me from doing so."

"Me too my friend, me too," the girl replied with a smile.

With a final nod, the Herondale turned on her heel and disappeared down alleyway, the black marks covering her body standing out against her tan skin boldly and brilliantly in the night.

A/N: Since I know that I will get a few questions about this, here are a few disclaimers:

-Whether NCIS is set later or TMI was set earlier is the reader's decision.

-This is set in late NCIS season 2, and long after TMI finished.

-I don't own either of these franchises.

I hope you enjoy this new crossover fic, I'm certainly enjoying writing it!

Louise :)