Iron Maw@ I'm say monster in general. if i recall right they already say about them in ch 1. The monster that devour human.(though ...i do mean something else as well).
About Tatsumi and Akame that can take after the boss I say this because....
Akame have the exp while Tatsumi have the potential power that is need in the future.
Also seem to me that i'm the only one that a realize what the author have done.
Spoiler for just in case:
Tatsumi friend get kill by a family of sadistic in ch 1.
Esdes a sadistic fall in love with him.
It's me or the author just like play with him