Shadow The Hedgehog
Introduced in 2001's "Sonic Adventure 2", Shadow the Hedgehog is an anti-hero version of Sonic the Hedgehog. Quickly becoming a fan-favorite among the Sonic family of characters, it was only a matter of time before Chris decided to "create" another Electric Hedgehog Pokemon...
Just as the Super forms in the Sonic Franchise are a blatant rip-off of the Super Saiyan transformation from Dragon Ball Z, Shadow the Hedgehog is basically a furfag version of Vegeta. Vegeta, in turn, is basically an outer space version of Marvel Comics' Prince Namor, the Sub-Mariner. Refer to the figure below for comparison.
Influence on Black Sonichu
Unlike Rosechu who is virtually identical to Amy Rose in every relevant respect, Black Sonichu only resembles Shadow in his color scheme and tenuous allegiance to the forces of evil. While Shadow is primarily motivated by his desire to learn about his mysterious past, Black Sonichu was informed of every aspect of his creation by Naitsirhc. Most notably, while Shadow is supposed to be a dark and edgy character, Black Sonichu is basically just a punk, committing blatant mischief for very transparent motives.
While this might seem to make Black Sonichu halfway original, it really only means that he's a poor copy of Sonichu instead of a slightly less poor copy of Shadow. Blake's only real claim to individuality was that he acted like an asshole; since falling for Bubbles in Sonichu #7, he doesn't even have that going for him.
Drummer for Christian and the Hedgehog Boys
A longtime fan of Chris's musical stylings, Shadow joined the group to replace outgoing drummer Roger Earl. While the Chris/Sonic/Shadow/Sonichu/Blake lineup quickly proved itself to be the "definitive" lineup in the eyes of most fans, internal tensions coupled with poor sales in the U.S. soon tore the band apart. Sonic and Shadow were reportedly fired from the group when Christian walked in on them 69-ing each other in their tour bus. Despite being a widespread rumor, in actuality Sonic left the band after important artistic differences, and Shadow supposedly met his death after a serious cocaine overdose.