I don't think I will be able to articulate this well, I might even another post that explains this better, but I really love Eren and Zeke's dynamic. It is a complicated and messy bond; I really do feel like they both wanted a brotherly relationship, even when everything around them prevents it. It is easy to think that Eren hates Zeke, end of story, but that really isn't the case.
Eren's expressions here feels like a small tiny break from the walls he has put up in Season 4. The way he relaxes when hearing Zeke come to help him, the way he softens his expression and look at Zeke with so much pity before betraying him, and how he looks over to the photo of Zeke's childhood. It is brief, but it gives hints that Eren's feelings about Zeke is more than just hatred.
He answers Zeke's questions truthfully, even when he didn't have to.
He also let's Zeke get closure with Grisha.
And go to him for relationship advice.
I also notice a pattern that whenever Eren "hates" Zeke it is usually done just after he breaks character.
He says this after he helps Zeke get closure.
He insults Zeke and tries to create a distinction between the two after answering his question on why he refused to do the ethunesia plan.
He tells Zeke he was manipulating and using him from the start after making that pitying expression (and immediately soften his eyes once he saw Zeke's reaction).
To me, it reads as Eren pushing Zeke away as he did with Armin and Mikasa. He needed to make himself seem like an uncaring monster for everything to work, but the thing is, Eren isn't uncaring, and these small details really show how conflicted Eren was about his relationship with Zeke. As much as he wants a close relationship with his brother, he also couldn't let himself be vulnerable and accept that he really did want Zeke's care and support.
"There's no way I could ever go along with a plan that messed up."
proceeds to commit genocide
