Do you know who Doomed-Terezi was talking about when she told John to write the message, "You don't need him"? Also, do you know why she sent her past self this message? (Other than to potentially prevent her past self from getting mixed up with Karkat and Dave in a rather odd relationship?)
Who specifically it was about is unclear. I assumed it was about Gamzee, but it could have been about Karkat or even Dave. I don’t think we’ll ever find out for sure.