ediff-mode-hook

ediff-mode-hook is a variable defined in `ediff-init.el'.
Its value is

nil

• This variable may be risky if used as a file-local variable.

Documentation:
Hook run just after ediff-mode is set up in the control buffer.
This is done before any windows or frames are created. One can use it to
set local variables that determine how the display looks like.

You can customize this variable.