Lyric discussion by TheVessel 

Cover art for Chlorine lyrics by Twenty One Pilots

From what I can gather, this song talks about dealing with abusive relationships. Being with said person is like drinking chlorine. It is poisoning him, slowly killing him. They have such a hold over him, he has become dependent on this person in his life. Hence; Venom on my tongue Dependant at times Poisonous vibration Help my body run The main bit of chorus(I'm running for my life) is about him running away from the relationship as he realizes what it is doing to him. "I love to hate the fight" is Tyler wanting to hold onto the relationship despite its consequences. This just my interpretation, but it is my best guess.

My Interpretation

Additionally, I realize that this lyric: I'm so sorry, I forgot you Let me catch you up to speed I've been tested like the ends of A weathered flag that's by the sea Could either be him begging for the person he was in an abusive relationship with to take him back, or Tyler begging the people he left for the abusive relationship to continue to take him in again. He's asking his old friends for forgiveness and help. It is more likely the latter.

@TheVessel all way off.

The song is about his mental Constitution and the inner struggle of OCD and anxiety/depression. The weathered flag is how those of us that deal with these issues feel all the time.