Since the player most likely cannot transform into a mind flayer (
https://forums.larian.com/ubbthreads.php?ubb=showflat&Main=92146&Number=704692#Post704692 )
It would be interesting to get such a companion at level 6-7 or later.
In the first act, we meet at least one non-aggressive mind flayer with whom we can communicate, which means there may be others. For example, a neutral mind flayer who has retained memory and personality, and therefore has to fear other mind flayers. The presence of such a character could fully reveal the theme of the mind flayers.
It would be an interesting experience, since it is impossible to create such a character in the editor, but the race is represented in the game and is sentient. I would even say too smart.
This shouldn't be a problem, as in Dragon Age Origin we cannot create Qunari, but we can take Stan into the party.