I think that this song is about, like many people already mentioned, is about a friend of the speaker's who is dealing with depressed or suicidal thoughts (I know you want to leave but friend, please don't take your life away from me). But, the speaker [Tyler] won't leave them alone, or is trying to help them by letting them know they are not alone ('Cause I just wont let go 'til we both see the light). However, by saying 'we both' this could mean both people are struggling and need each other to try and keep going.
I think that this song is about, like many people already mentioned, is about a friend of the speaker's who is dealing with depressed or suicidal thoughts (I know you want to leave but friend, please don't take your life away from me). But, the speaker [Tyler] won't leave them alone, or is trying to help them by letting them know they are not alone ('Cause I just wont let go 'til we both see the light). However, by saying 'we both' this could mean both people are struggling and need each other to try and keep going.