[Fish]

Nerdy comic backstories about the boys... Potentially major spoilers...

Spoiler!

The boys Thomas and William eventually become the heroes Speed and Wiccan. Thomas and William were twins supposedly born to Scarlet Witch and Vision; in reality, they were magical constructs, created by Wanda's hex powers. It was revealed that she used slivers of Mephisto's life essence to give her children souls. Tommy and Billy were eventually reabsorbed by Mephisto and ceased to exist.

[...]

The Scarlet Witch used her reality warping powers to create twin sons, unknowingly, from two (of five) scattered fragments of the soul of the demon Mephisto that were previously lost to him in an ill-fated encounter with the powerful mutant child Franklin Richards(Fantastic 4's Reed Richards' son). When the boys' souls were reabsorbed into Mephisto, because of the power Wanda put into the soul fragments, they destroyed him and their souls were reincarnated as Thomas Shepherd, the Young Avenger Speed, and Billy.

Both boys have a really long and crazy history with multiple different Avengers comic lines.

Sidenote, in the comics, William(who becomes Wiccan) is one of Marvel's first homo character.