5 seconds of summer is a band, also known as 5SOS. Just because her tumblr is full of talk of being a slut and having sex, does not mean she is actually doing these things. When people are asking for "ships" and "requests" it is just requests for a story and a ship is just a slang term for two people who you like together, for example: Bradgelina is the shipname for Brad Pitt and Angelina Jolie.
'muke" is a ship name of two of the boys in the band, Luke Hemmings and Michael Clifford. "The feels" is another slang of just being completely overwhelm with emotion. All the black clothing does not mean she is goth.
All this is normal and perfectly healthy, it is a phase. I think that you should let her continue having a tumblr because she isn't hurting anyone and again, it is just a phase.
There's nothing more disrespectful than going on your kid's social media if they didn't want you too.
I cant really gove you an answer,but what I can give you is a way to a solution, that is you have to find the anglde that you relate to or peaks your interest. A good paper is one that people get drawn into because it reaches them ln some way.As for me WW11 to me, I think of the holocaust and the effect it had on the survivors, their families and those who stood by and did nothing until it was too late.