Tatsumi deserved better.
The more I think about it, the more I believe Tatsumi was just a plot device, a way to introduce the story to readers (Tatsumi, like the reader, is ignorant, so the author can explain the story without forcing it, telling us about the corruption in the empire, the Teigu, and introducing all the characters), to make us fond of (through harem-comedy scenes) poorly developed characters (Sheele, Chelsea, and Leone), to humanize and make some characters more likable (Esdeath and Mine), and, finally, to push the story in a certain direction (he advocates for the defeat of important characters like Budo and Esdeath).
Seriously, Tatsumi was treated terribly, he doesn't have a real final enemy (even Mine has a final enemy like Seryu), he doesn't have any cool fights (even Wave has a cool fight like the one with Syura, Tatsumi gets kicked for half the manga, then evolves Incursio and becomes the support of the night raids, helps Mine kill Budo, helps the night raids destroy the last wild hunt and avenge Lubbock, but it wasn't him who killed Izou but Akame, it doesn't matter that Lubbock died indirectly because of Tatsumi so it would have been better if he had killed Izou and helped kill Esdeath, the final / most important and strongest enemy of the manga, it doesn't matter if he was the character closest to her and it would have made more sense if he had been the only one able to move during the time stop and the boy she loves who defeated her, which would have more justified the fact that Esdeath had lowered her guard / taken it easier / committed a mistake) and doesn't even choose the girl he wants to be with (in fact he settles for the first sane girl who confesses her love to him).