Sinnona aka Sin the hedgehog

Silent as the night, swift as the wind she never fails to hit her mark
 
Name: Sinnona the Hedgehog
Nick/codename: Sin
Age: 19
Status: freelance assassin
Weapon: Lasark (futurist long bow with arrows made of lasers)
 
Sin is a quiet mysterious girl makes a living by killing. She both is and isn't a mercenary because some of the killings are for her own reasons. Sin started killing because of an accident that blew up her home town 16 years ago. She knows who is responsible but isn't sure that she really can kill the culprit. (The incident was Knuckles in Tails's lab playing with the chemicals that resulted in the creation/alteration of Ainoko.) Sin knows that if she goes after Knuckles that Tails and Sonic will stop her so she tries to think of a better plan.
 
Her plans eventually lead her to run into Ainoko. At first Ainoko's happy-go-lucky attitude annoys her but after awhile she lets him in. She explains why she wants to kill Knuckles to Ainoko (who she doesn't know is Knuckles son) and asks for his help. He refuses because of who they are up against and she goes to leave but he stops her and asks,
 
"Why do you do it, Sinnona, why do you kill?" She replied,
"Why? For my family, for everyone I lost that day due to that wretched echidna."
"You're family was killed by Knuckles explosion?" She shook her head,
"No, my parents were dead before that, I was talking about my cousin Crystal Life." 
 
Well long story short Crimson Ice joins Sin and Ainoko for his own reasons and together they create Team Def-con in order to attack and defeat Team Sonic. Only  one problem, Sin doesn't know that Crimson Ice is in fact Crystal Life. The only thing that stands in Team Def-cons way of revenge is...surprisingly..Team Dark lead by Shadow. Apparently Shadow knows things about what happened 16 years ago. Like the fact that the chemicals Tails was experimenting with was gene-splicing.(Hence Ainoko having Tails's twin tails.) He also knows that Knuckles isn't responsible for the explosions...