Rachel Berry (Lea Michele) is singing an original song written by Darren Criss for her last performance on Fox's Glee.

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The series finale of Glee will feature Rachel singing her final song and it will be an original one. Co-star Criss (who plays Blaine on the series) wrote a song called This Time and it will be the last song Rachel sings.

The cast and crew of Glee appeared at PaleyFest Friday night where they talked about the song. Michele that no other song "could have encapsulated the whole experience" of Glee quite like This Time.

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"That was the day I fell to my knees and cried," Michele recalled. "I got to say everything to everyone that I always (intended) to say but you can't think of the words. And he wrote them."

Criss said that his "main thing was to write a song for Lea. It's not just my own vanity." Essentially, the song is "a love note for the entire series."

Michele said that ultimately her favorite song she ever performed on Glee was Faithfully by Journey, a song Rachel sang at Regionals with Finn (the late Cory Monteith) during the season 1 finale.

The two-hour finale event will feature the final two episodes of Glee, titled 2009 and Dreams Come True, suggesting a happy ending for many if not all the characters.

Glee will wrap up with its two-hour series finale on Friday, March 20 at 8 p.m. ET/PT on Fox.

Watch the promo for the final episode of Glee here: