Just like Frisk, Chara is an easily impressionable child

This is the most baseless out-of-character assessment you can possibly make of Chara's character and is something you just read into them. If anything, Chara is the least impressionable character in the entire game. In their backstory they're the only person willing to actually bone up and do their plan to cross the barrier, whereas every other character in the entire game more or less folds on their convictions or desires to win confrontations because Frisk is particularly nice or insistent, or in Asgore's case, because he's just weak-willed. Chara is also, at full strength in the Genocide Route, capable of overriding the player's control.

Chara's core character trait is that they are strong-willed and know what they want to achieve, and they will do it. Interpreting Chara in this way is literally at odds with the only actual canon character trait they possess at all.

In any case,

This is why the narrations become evil in the genocide route but stay neutral in the other routes.

I linked to my Big Anti-Narrachara Theory in my root comment, and there I point out that actually the Genocide Route's narration is often identical to the True Pacifist and Neutral Routes' narration, which is one of the main issues with Narrachara. If Chara were meant to be portrayed as developing as a character differently between the different routes, we should expect the narration as a whole to change, but the narration instead only changes at very specific parts, which indicates that the narrator is just a generic entity but Chara "talks over" them in the Genocide Route at certain points.

Also claiming that chara only becomes the narrator in genocide supports the common evil chara misconception, which is just stupid

Narrachara at this point is arguably more common than the "Chara is evil" theory which is honestly a crying shame because it's far from reasonable. I'm not saying that Chara "just being evil" is a very good interpretation (it's overly simple), but it's a lot stronger than Narrachara.