How to not suck at jeff the killer fanfictions

Vicente

Heads up to those reading, English isn't their native tongue

Name: Vicente (call him Vincent if you want)

CP name: Bad Blood

Age: 14 years old

Species: Human

Appearance: Short black hair, grey eyes (they used to be bluish-green)

Clothes: He always wears a black hoodie, navy blue jeans and black converse. (Also, he has a kind of bandana in his neck, I'm not sure how to say it in english)

Height: 1,65 mt. (Unsure)

Weight: 51 kg. (Unsure)

Backstory: Vicente was a normal boy, he had good grades, but not so many friends. He always liked Creepypasta. Near summer holidays, one of the teachers told the class about an experiment about blood coagulation that was being held in a laboratory outside the school. After class, Vicente was the only one that went to the teacher to ask her if he could take part in the experiment.
A couple of days later, he went (alone) to the laboratory (near the woods). It looked abandoned, but he saw a piece of paper that asked the volunteers of the experiment to please go inside. He went in, somebody knocked him out and later he woke up in a strange room. He wasn't tied or anything, so he got up and he saw "the doctor" and his assistant. He punched the doctor, leaving him unconscious, while the assistant watched. Vicente realized that there was blood coming out of his wrist, it's black. Suddenly, the assistant told him that he could do whatever he wanted with "the doctor", since it's his fault. Vicente heard a voice in his head saying: "think of a weapon". He thought of a sting (I don't know how you call it) and the blood in his wrist took that form. He decided to kill "the doctor", and ended up causing his body to explode in blood and guts. While the assistant turned around to vomit, Vicente laughed maniacally, before killing the assistant too, because the voice in his head told him to do so.

He got out of the laboratory, almost instantly feeling his phone vibrating: it was his mother. He dropped the phone and destroyed it with his blood. Then, he walked into the forest claiming that Vicente died and now he is Bad Blood. Now he kills people just for his own amusement.

(By the way the voice in his head was gone. And then he met Zalgo and went to the creepyhouse, but I refuse to write all that)

Weapon: His blood

First off, you're English is actually very good even though it isn't your native tongue, you'll have to tell me where you're from!
The bandanna thing I'm guessing is like a scarf, and the age isn't cliche. It's actually quite interesting to see a younger age
The height and weight thing I'm unsure about but that's okay,
It's good, the background is pretty interesting and very detailed. I like that,
This is actually a good character, maybe change up the clothing a little bit but other than that, you've got yourself an A+  OC!