Headcanon for Grievous with an S/o he found marooned on some outer ring world? Like, she's been alone so long she forgot how to speak and had a very innocent demeanor.
• he would probably get frustrated that she doesn't know much but once he realizes what's going on he'll calm down
• he'd still be a little impatient though, but he'd try to keep his temper in check
• despite his impatience, he would try to teach her the things she needs to know
• after a while he'd actually have a lot of fun teaching her, especially once she starts grasping things
• successfully teaching her to write would be very exciting for him because writing is one step closer to speaking
• since he still has a job to do, he'd have someone look after her till he can come back
• he'd be hesitant to let her roam around until he knows for certain she can navigate his ship safely
• once she's learned to write, speak, and read, he'd move on to teach her a little sword fighting so if she does ever end up lost somewhere again, she can at least fend for herself until he can find her