A big backstory goes behind this character, I've thought hard on this
Drew this in math class... because I can!
It might spoil some parts: I've mixed original storyline with extra events
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//After the Nibelheim accident//
Hojo kept trying to create the ultimate SOLDIER.
He managed to get the last remaining DNA from Sephiroth.
All other SOLDIERS got killed, except fot Zack.
So Hojo wanted to use Zack's DNA for his newest experiment.
However, a clumsy lab assistant gave Hojo some DNA from a different specimen (Cloud). Hojo never noticed and kept experimenting.

There wasn't enough room for his newest experiment, so he moved the testtube containing the clone to the lab in Midgar. There, a few other professors cooperated with professor Hojo...
They decided to call it "Project Azrael"

//6 years later//
After Zack and Cloud had escaped, Hojo kept working on the project.
At this time, Hojo noticed the clone looked like his failed experiment, with a few traits from Sephiroth.
Angry about the mistake, he "disposed" of the assistant who caused it. But he kept working on the project after that.
However, the body of the experiment started to deteriorate, until only the upper body was left.
Hojo abandoned the project and left without a trace.
The other professors didn't want to give up on Project Azrael, and kept looking for a solution.

A few days after, a mysterious young man named Adam appeared before the professors, showing them a mysterious object.
Without explaining what it was, he left as quickly as he came.
The professors had no other choice, they infused the object with the experiment's heart... then the heart suddenly started beating again!
Not only that, but the experiment's body started to repair itself!
The people working at the lab were overjoyed, but that joy didn't last long...
Mysterious men infiltrated the building and started to destroy everything!
Many people working there got killed, some survivors managed to hide Project Azrael in the emergency room.

//5 years later, present//
A mysterious girl looks around the ruins of Midgar, then arrives at the destroyed lab.
Looking for scrap parts, she finds something else instead: a secret passage!
A big metal door with the words "Project Azrael" on it blocks the entrance, but it was so rusted it was easily removed.
She couldn't believe what she saw inside...