Something that'd be neat as heck is if the mind control wasnt just "YOU'RE CONTROLLED/YOU'RE NOT!", but some degree of inflicted mind control that stacked if resisted the first time. It'd be evident by decreased LoS as the character becomes less able to focus, or messages regarding the character in question experiencing some serious confusion/mental effects.
Having psionicsl be a resisted/not-resisted thing is reasonable gameplay wise, but if the engine permits you can do some really unique stuff with it I imagine.
Let hallucinating not just be a message, but make the character taking random Overwatch attacks at nearby terrain/scenery to illustrate the slow loss of control as the alien achieves dominance etc. That accompanied with that decrease in LoS etc will demonstrate that the character isnt fully under your control, but in turn isnt fully dominated either... but they've become a liability until that stacking psychic dominance is relieved.
EDIT: To above poster, yeah its technically working as designed... but I'm also of the opinion that that isnt a good thing necessarily. You cant really counter/prepare for it, and its random nature that operates without LoS feels primitive and just annoying IMO. But the community wanted it to be as such during development apparently, so the devs complied. Democracy has failed us