"
If I didn't have you there would be nothing left,
The shell of a man who could never be his best.
If I didn't have you, I'd never see the sun,
You taught me how to be someone, yeah
This song is about the band and their fans, so Louis is saying that without us Directioners, there would be no 1D at all. Just 4 guys trying to make it in the music industry, with no reward. They couldn't be as successful without us. The 'sun' could be the fame. Without Directioners, they wouldn't be famous, never would have known the fame. We helped them know that they could make it.