I have barely picked up the game and I have gone through the TRUE Pacifist ending of Undertale and am kind of deep into the Genocide Route already. So I would like to know if anything changes if you name the human “Chara”. I tried Google, but that didn’t have anything I could work with.
The only change is that you receive unique text when asked to confirm the name 'Chara' in the name selection menu. This does not affect gameplay on any route. Source is the Undertale Wiki page.
There is only one name that changes gameplay after confirming name selection, but with this name, a Genocide route is not possible. It is