Why was the scene of Levi threatening Historia removed?
My initial response to this question was going to be that there inevitably have to be cuts when a lengthy manga is adapted into an anime and it's not uncommon for some nuance and character complexity to be lost along the way in order to make space for more action. However I couldn't actually remember how this scene plays out in the anime, so I went back and watched it again to compare it to the manga, and I realise now that they didn't just cut this scene, they actually rearranged the whole sequence of events.
In the manga, this scene takes place in chapter 56 Actors right at the beginning of the Uprising Arc. Hanji and Levi are in hiding with the 104th and have spent the previous day torturing Sannes into confessing that the Reiss family is the true royal bloodline. The following morning Nifa arrives with orders from Erwin that Historia must take the throne as part of his plan to overthrow the government and the puppet king. Dimo and Flegel Reeves have also just arrived on the scene, tensions are running high and there’s a palpable sense of urgency that they must get their plan underway before their enemies discover what they are up to and start moving against them. Historia has no idea what is going on because Levi “forgot” to tell her. Levi's face here will never cease to crack me up.
It’s hardly surprising that Historia is reluctant and Levi is pissed. Not that that excuses his behaviour, but it’s a very Levi way to react. Erwin has given an order and he’ll be damned if it isn’t carried out. Also Levi knows, better than any of the 104th what’s really at stake here, that’s what his amazing “lunatic” speech is about.
Things play out quite differently in the anime. Levi doesn’t tell Historia that Erwin’s orders are for her to take the throne until episode 45 Outside the Walls of Orvud District. This is effectively 11 chapters after it takes place in the manga. By this stage Historia has already been kidnapped, reunited with her father, recovered her memories of Frida, learned the truth about her family and her lineage, survived the events of the Reiss chapel, seen her father turned into the Flaming Chicken Titan, and retreated with the rest of the Survey Corps to Orvud. She already knows she is Historia Reiss, that she has royal blood and is the rightful heir to the throne. So although she is shocked when Levi conveys Erwin’s order, she doesn’t hesitate to calmly accept.
This is very different from her reluctant, panicked agreement in chapter 56.
This is just one of a number of changes that were made to the Uprising Arc in the anime. As far as I can recall Isayama had said that he was always dissatisfied by the arc so he saw the production of the anime as an opportunity to amend it. Most of the changes simplify the timeline of events, which is no bad thing, though unfortunately some character nuance was lost, particularly in Levi’s case here. This is just my opinion, but I suspect another reason for this change was to give Historia more agency. By the time she is presented with the order to become queen she has already recovered her memories and willingly accepted her destiny. This just makes her subsequent loss of agency in the final seasons all the more frustrating.
