Literally anything about Newt being involved in the war. Stories about him training dragons for war and hating himself for it. Or about fighting himself. About getting letters from his war hero brother out in the trenches and being both ashamed and grateful he avoided that. Maybe he was pressed into service and really didn't want to fight at all? Performing magic in front of so many muggles to just keep them alive - maybe why he didn't obliviate Jacob immediately was just force of habit from the war. Maybe he avoided WWI because it was just political squabbling that he disagreed with but then when WWII comes around he can't just sit by even though fighting kills him a bit inside. Just anything about Newt fighting in the war.