The Spider's Shadow

Peter Parker has had a lot of things go wrong in his life, his twin sister, Petra Parker, is no different. Between the two of them, they've got PTSD, have had panic attacks, several stab and bullet wounds, buildings collapsed upon them, and the like. The twins often get bullied for being the only orphans in their school, but it doesn't bother them, after losing their uncle in a robbery, nothing bothers them anymore. Petra is the quiet, reserved, sensible twin. She tends to keep to the shadows. Peter on the other hand, is the bright, bubbly, attention-grabbing kid. You can tell because Peter is the one who swings around in spandex being flashy and jokey while Petra sticks to the shadows, only coming out in black, and although she never speaks while saving her twin's butt, you can tell that they are communicating. Staying back and letting her twin have all the attention means no one knows she exists, however that doesn't stop her from being smart, snarky, and making all of her brother's tech! Well, until Tony Stark enters the game. Tony whisks Peter away to Germany, and lands him an 'internship'. Those who are in the know about Spider-Man think Petra doesn't know, and only Fury, who is training Petra to take over SHIELD, knows about the Shadow Spideress. What happens when the Avengers meet the Shadow Spider for the first time?

Collaboration with @Silver-pool