Characterization
Actress Katie Cassidy, who portrayed Ruby in the third season, described the character as an ally of Sam and Dean who "also likes to stir up a little trouble." Ruby is "manipulative" and in control of her situation. Claiming to have been sent back to Hell after the third season finale, Ruby seems different after she returns. In the words of Cortese, who played the character in the fourth season, Ruby did not walk in saying, "I'm going to kick everyone's ass and be tough," but was rather a "total 180 from last season". Cortese had auditioned for an unnamed "love interest", and the actress felt the character fell in love with Sam throughout the season. However, she questioned whether this was "true love" or her being "in love with what he can do". Ruby nevertheless reveals herself as a traitor, an aspect Kripke intended from the beginning.
Read more about this topic: Ruby (Supernatural)