User blog comment:Paul.rea/Teen Wolf News 051816/@comment-27038309-20160520072526/@comment-26879545-20160520223208

"He broke the pack and killed Scott. That alone is something no other villain accomplished."

He broke the pack because Stiles kept his killing of Donovan a secret. Then Theo fed Scott a totally BS story that Scott shouldn't have believed considering he and Stiles were friends for like... ages, apparently.

Also, the actions of Jennifer Blake led Scott, Stiles and Allison to a temporary death as surrogate sacrifices, so... Jennifer technically caused the deaths of three main characters before Theo even showed up.