(I kinda got attached)
Virulent is the future descendent of Scourge and Fiona, thus explains how he got the jacket, and is still alive.
Through the events of iblis and what not, he is the only descendent left in his family, and being entrusted to Shadow as his legal guardian from a very young age, he has a love hate relationship with just about everything.
Favorite thing to do is tinker and build (making everyone believe that he is Tails' descendent, but he'll deny it every time)
(No! Shadow didn't ask for it, he very much hated said idea, but ended up likening him anyways)
And I probably know what you're thinking, but no, he and Silver aren't very good friends.