This spring, Grey's Anatomy introduced a lesbian story line with a romance between the confident, sexually voracious Callie Torres (Sara Ramirez) and the professionally ambitious yet personally restrained Erica Hahn (Brooke Smith).

The plot line, culminating in the season finale, "Freedom," offered both the drama Grey's Anatomy has become known for and a groundbreaking truthfulness network television has rarely achieved when it comes to lesbian relationships.

For Callie and Erica, the season ended with a passionate kiss...

With that kiss, Callie and Erica became the only regular lesbian or bi-sexual female characters currently on network television.

This is also the first time that two regular stars on a network show have begun a lesbian romance, as opposed to one becoming involved with a new lesbian character introduced expressly for that relationship.

To prepare for the story line, which will continue next season, the Grey's Anatomy producers consulted with GLAAD, which worked with the series on a previous story line about a transgender character with breast cancer.

To read more about how the Callie-Erica story line was developed on Grey's Anatomy, and for hints at what's to come, follow the link here ...

Steve Marsi is the Managing Editor of TV Fanatic. Follow him on Google+ or email him here.