Not sure if this has been pointed out before, but “Fire Fire” and “Scary World” (especially their choruses) go strangely well together :Oa Sped up the latter and just cut out a bit of the former to make the comparison more obvious.

Pretty sure they’re in the same key, but the chords are a bit different, which is why the instrumentals kind of clash. BUT if you just isolate the melodies…  I’m sure they’d sound pretty awesome. If someone decides to make some kind of medley, well, here’s one of your transitions haha.