@snowfist I was thinking the exact same thing. And it wasn't just after Head Movies – when they published the very first single (Technicolour Sky), the description for the band on iTunes said something close to "fuelled by mutual heartbreak, the band wrote and recorded twelve songs in fourteen days", referring to the Sweet Delirium album. I also found a playlist of Steve's on Spotify recently labelled 'Delirium Ref' and another one labelled 'Ozwald Ref' that were both last added to in March 2018, so whatever this heartbreak was must've been in the late '17, early '18 range when the duo was formed.
Deluge feels oldest to me for that reason too. It'd be great to hear the stories behind these songs the way he did for Paper Cuts for sure! Perhaps some of the meanings hit too close to home for him to comfortably go into detail...