For those that still don't get it. (I myself I'm kind of like that) We learned in this flashback arc's chapter that:
1. Cross Marian knew form the very beginning who The Millenium Earl was in terms of physical appearance and was keeping tabs on him. How, Why, and When? Who fucking knows???
2. Turns out Mana wasn't Nea, or the 14th or whatever... IT WAS THE FUCKING EARL WHO LOST HIS MEMORIES DUE TO TRAUMA. Welp, shit. Also, apparently the Earl ate Nea... Wha--??
3. Apparently Nea was implanted into "Allen" 30 years ago, so because of that, Marian discards Allen (Red) as a suspect because he's a child. Uuuuuhhhh.... Yeah, about that.... More questions....?
4. Allen (Dog) Is an asshole. No, really.