(Pardon my terrible art, I'm 15 and trying to get better)
Alessandro Di Sante Is an awkward and shy Italian 15 years old boy who was orphaned at the age of seven and adopted by a family who moved to NYC when he was 12. 
While walking through Manhattan, he came across a fight between Rhino and Peter Parker's clone Kaine. Alessandro was seriously injured when a car thrown by Rhino crashed into him. To save him, Kaine decided to give him a transfusion of his blood. After that the boy developed spider-like powers and an incredible healing factor, not as strong as Deadpool or Wolverine but still very efficient. Immediately Alessandro began to use his powers for good under the identity of Arachnid. 
Peter Parker and Kaine taught him how to be a good hero, although both were quite protective of the boy given his young age. 
Arachnid's worst enemy is Black Tarantula, who in this universe is much more powerful and much more ruthless than his 616 counterpart. In this universe, Jack Lantern works for Black Tarantula and he often gets into fights with Arachnid. During one of their fights, Jack Lantern accidentally kills Alessandro's friend Sophie. While trying to get revenge on Jack, Arachnid finds out that the villain is actually his best friend Matthew, so he spares his life but never talks to him again. 
Seeking for redemption, Matthew sacrifices himself to save Alessandro from Black Tarantula and dies in his arms.
To revenge his friend, Arachnid steals Doc Ock's costume when he was the Superior Spider-Man and goes to face Black Tarantula. During the fight, Alessandro is about to kill Tarantula, but he realizes that, killing him won't make him better that him, so he leaves him on the ground, but while he is walking away, Black Tarantula shoots bullet to him. Arachnid dodges it and the bullet bounces on a glass and goes back to Black Tarantula, killing him. 
After that, Alessandro keeps the suit and the name of Superior Spider-Man and continues saving lives and fighting crime.
If you have any suggestions for improving the story or any future enemies Superior Spider-Man might face, please share them with me.

Meet Alessandro Di Sante, Arachnid (TRN-106) (read desc)