"Warrior" is a song by Demi Lovato which appears as the thirteenth track on their fourth album, DEMI. Demi calls the song "the hardest and most easiest song to write". When the release of Demi was announced, it was said there would be a sequel to "Skyscraper". Warrior is that sequel.
In this song Demi expresses that they want to move on without letting their past (or maybe even their abusive father) disturb them any further. Even though they know that they'll never be able to forget about their past because they not only have metaphorical but also real scars, this song shows a very determined side because Demi is sure that nothing and no one can hurt them as much as it used to.
On May 9, 2013, in a track-by-track Billboard review, writer Jason Lipshutz stated: "Most of "DEMI" sidesteps the personal struggles -- and Lovato's triumph over them -- that she laid out on "Unbroken" but "Warrior" serves as a follow-up visit to "Skyscraper" territory, this time with the singer declaring herself a phoenix that has risen from all-too-public ashes. "I've got shame, I've got scars, that I will never show/I'm a survivor, in more ways than you'll know," Lovato sings like a piano line volleys with a cello." 
Demi performed "Warrior" at the 2013 Dignity Gala on October 18. "Warrior" was a part of the setlist for Demi's Neon Lights Tour.
Demi Lovato - " Warrior " ( live for the first time )
2013 Dignity Gala
Warrior - San Jose
Neon Lights Tour
This is a story that I have never told
I gotta get this off my chest to let it go I need to take back the light inside you stole You're a criminal And you steal like you're a pro
All the pain and the truth I wear like a battle wound So ashamed, so confused I was broken and bruised
Now I'm a warrior Now I've got thicker skin I'm a warrior I'm stronger than I've ever been And my armor, is made of steel, you can't get in I'm a warrior And you can never hurt me again
Out of the ashes, I'm burning like a fire You can save your apologies, you're nothing but a liar I've got shame, I've got scars That I will never show I'm a survivor In more ways than you know
Cause all the pain and the truth I wear like a battle wound So ashamed, so confused I'm not broken or bruised
'Cause now I'm a warrior Now I've got thicker skin I'm a warrior I'm stronger than I've ever been And my armor, is made of steel, you can't get in I'm a warrior And you can never hurt me
There's a part of me I can't get back A little girl grew up too fast All it took was once, I'll never be the same Now I'm taking back my life today Nothing left that you can say Cause you were never gonna take the blame anyway
Now I'm a warrior I've got thicker skin I'm a warrior I'm stronger than I've ever been And my armor, is made of steel, you can't get in I'm a warrior And you can never hurt me again