This also gives Marvel the option to include Nicholas Scratch in future franchises such as the rumored ‘Sons of Midnight’ project.
The overwhelming consensus is that Nicholas’ mother, Agatha, is clearly present here in the form of Wanda’s pesky and overly exuberant neighbor, Agnes.
In the comics, Nicholas Scratch was a very capable and dangerous sorcerer and was often an antagonist to his mother Agatha, and her ideals.
This scene explains that Shield had been working with Mephisto on the Tesseract project prior to The Avengers.