Shadow is a Violinist in the same orchestra Amy attends. Of course, when he and Sonic meet, they instantly become rivals, with the Violinist hedgehog's rough and dark demeanor greatly contrasting against the snarky and sarcastic scientist's own. 

Shadow would sound much like his game counterpart: Dark, brooding and, as Sonic would put it, a stick in the mud.

Although his role is minor, most of Shadow's lines are directed as harsh jabs at Sonic. 

Voice clips of Shadow for reference: https://youtu.be/VfVXJUeMIKs