I want to say that I have made a discovery!
In book eight they said that Larkin was killed by serpine but he was killed AFTER hopeless.
And Ok if that was it end of story nothing more BUT it says in Armageddon Outta Here that hopeless helped them chase serpine. Which makes no sense because it said that the war was ending and if it was ending then hopeless and larkin should have been dead. This is supposedly the last time they see serpine until the first requiem ball. If this is true then neither Larkin or hopeless should have been there.