For more of all things Reign, be sure to get the season pass for Supergirl Season 3 on digital retailers.
In this exclusive clip, we see that Sam was originally intended to transition into Reign much earlier in her life.
If Sam had not found herself pregnant as a teenager, Reign might have arisen long before Kara had the chance to become Supergirl.
Ruby was never supposed to exist, and so she was the variable that kept Sam tethered to humanity rather than becoming a Worldkiller for such a long time.