Clarke Griffin was one of the original one hundred teenaged delinquents sent down to Earth to test if it was habitable again after a nuclear apocalypse destroyed it almost a century prior. She is portrayed by Eliza Taylor on the CW show based on Kass Morgan's The 100 novels.
Clarke has a number of romantic moments, flirtations, and partners. In season 2, she shares a kiss with Lexa, making Clarke the first LGBTI lead on a CW show. It also made her one of a handful of bi leads on television.
The kiss was brief and some viewers of the show felt that Lexa had initiated the kiss, and insisted that Clarke is still heterosexual.
Showrunner Jason Rothenberg discussed the need to make Clarke's bisexuality clear in an interview with Vanity Fair.
And she was probably [having sex] and drinking her way across the post-apocalyptic earth, to try to escape. That was escapist sex in that first episode. I knew that was going to happen. At first, I didn’t know whether it was going to be a male or a female partner. But it did become important to make it a female partner, because I felt like it needed it to be clear that she is bisexual. I usually don’t make decisions based on that. But I didn’t want there to be any doubt about it.[1]