Sir, would you rather move or have your occipital lobe bashed in with a shovel?

-Is what I would ask if I had functional vocal cords, something I currently do not have. The young man, about 17 or 18 by the looks of it, seems to be playing some sort of game, one hand on the arrow keys and the other on the asdw keys. Sitting with his back hunched like some 15'th century bellringer, long blond hair obscured partially by a beanie, the very picture of someone with nothing better to do than hang out in a library, playing some sort of puzzle game.

...If I take a closer look at his disgusting display, it seems he is actually controlling two separate characters in the game, one blue and the other red. Not only is a radical gamer, but also a friendless one. With all the facts presented, once would reasonably be able to believe that he is also a virgin.

Nobody would miss him. I glance around, but there are people about on this floor. Curses! A full-frontal attack wouldn't work, since I need to use the computer for a good while. Can't have heroes or villains or lawmakers busting in on me.

Alright, alright, no villain manoeuvres, nothing like that. No grabbing his neck and floating into the air, choking and sucking his blood at the same time. Hrm. When the path of a villain is impossible, the only other choice is that of the civilian.

I step closer, making my presence known. He doesn't even glance at me. If anything, his back only hunches even more, taking on the optimal cheese puff form, neck stuck out in the perfect angle to allow for a clean beheading. As his hair drops forward slightly, greasy and unwashed, I notice how just a small bit of skin has become bared to me. Pale as a vampire.

This might just be the worst mistake of my life. That is, assuming that his first thought is "wow I bet this guy is a humanoid amalgamation of 200 000 mosquitos".

A glance to the left, a glance to the right. Nobody's looking. I slide off my right glove, exposing my three-coloured "skin". If I look closely, all the mosquitos are moving, if only slightly. Bare your fangs, my flesh. Let's show him the power that inhabits us all!

I bring my right index up to my face, observing how the smooth surface slowly grows spiky and bloodthirsty as the Vampires ready their proboscises. Another glance around me. Nobody has noticed. Slowly, surely, I lower my finger towards his exposed neck, that soft little patch of pale...

"-Dude, what are you even doing?"

You would not believe with what speed and agility I retracted my hand and thrust it into my glove.

"..."

Stolen from its rightful author, this tale is not meant to be on Amazon; report any sightings.

His eyes narrow just slightly. His face is as pale as his neck, and there are just the slightest tufts of orange-ish hairs on his chin, typical for a teenager. I realize now that this would be the perfect moment to ask if he could move, but that is a problem for me. Of course, I could speak and blame my odd voice on some foreign accent, but this guy looks like the sceptic type, what with how he's looking at me and all.

...Please stop looking at me like that. Please, sir, I just want to-,,

No, stop! Body, do not retreat now! As intimidating as this mere teenager may seem, we are more than he is! We could suck a monkey dry and revive him as another subject, keep your wits!!

With that rallying cry, I was able to keep myself strong on my feet, even when faced with the glare of a stubbled youth. 

"...Umm, if you want the computer, just use some other one, I'm kinda busy here, yeah? Scamper off, weirdo."

Well, that's quite rude. Just because you said that, I'm going to stand here. Being right in the way. Maybe even take a step closer to him just to-,

"You are seriously the most suspicious person I have ever seen. What are you, three racoons in an overcoat?"

If I could sweat, I would. Mister, I am literally two hundred thousand mosquitos in an overcoat. Don't phone the fire department. But if you must know, I smoked this Juul...

The youth turns his torso, slinging his arm around the back of the chair to get a good look at me. 

"Um."

He turns back to the screen and exits the level. 

"Yeah, okay, go get 'em, champ vamp."

Saying so, he stands up, doing a little bow and shuffle to present the chair to me. I glance at him. And then the chair. And then back to him. He returns my glance. 

Well, uh, okay. How-, how wise of you, civilian! To think we still had youths with some sense in their little drug-shrunk minds! The boy may have said "champ vamp" in the most derogatory of ways, but I took to the title whole-heartedly, sitting myself down with all the gravitas of a true-blood. This gesture included letting my slouch-coat twirl just slightly, and making some flourishing movements with my hands. To say I didn't make a few hundred mosquitos specifically lift the brim of the overcoat to make it move as if by magic would be a lie. 

Aha, yes! Finally, a computer! First up, I need to make a few calculations, namely in regard to my mosquitos. How much is a single point of blood? How many mosquitos do I need to such a human dry, and, more importantly, how much will I need to absorb a whole bag of blood?

Let's see here... I quickly exit the game and hop over to google. Hrm. On a further note, I'd better use duckduckgo for this. More secure. 

...It seems a normal mosquito can absorb 0,000005 litres of blood. 189 000 times 0,000005 is... 0,945 liters. 

0,00005 times 29 000 is 1,45 liters, and 0,0005 times 5 800 is 2,9. 

In other words, one point of blood is 0,0000005 litres of blood, all of my Mosquitos can absorb about a litre of blood, all my Bloodsuckers can absorb about one and a half, and all my Vampires can do a total of about 3 litres. All and all, they could absorb 5,295 litres of blood. 

Hmmm.

"...How much blood in a human body..."

Oho. Ohohoho! With this much, I should be able to suck a human dry~!

"Zzzzzz..." 

With a buzzing sigh, I lean back, contentment growing. I know I almost died there in the beginning, but... Man. I could not have wished for a better power. 

But! We still haven't gotten to the main course!

How much blood in a blood bag, how many blood bags in a blood bank!!

Hmmm... 

By the looks of it, 3 dl per blood bag, or 0,3 litres. Ey, maybe this heist is possible after all!

Hrm, not much information here... Especially not if I search up the hospital in this city. Sure, there's a blood bank in there and they do accept donations, but exactly nothing about the quantity of blood. We'll assume they have, oh, about 100 bags, at least. I really don't need to steal all of the blood by absorbing it. As a matter of fact, I can just as well have some mosquitos simply lift them!

Yees, alright, hehehhe, alright! Next evolution, I'll create an army of Vampires and Bloodsuckers, and I'll have the normal mosquitos simply carry the bags out of there!!

My genius is... Frightening, sometimes.

Alright! Enough computer-watching, time to get evolving!

Saying so, I stand up, and head back to my lair.