I hope grumpiness will not be one of movie Shadow traits.
First - the Shadow we love most (SA2/Heroes/06) was not grumpy. I don't remember him acting annoyed by the smallest thing or being snappy. Still rewatching those scenes he seems more calm, cool-headed (in that case the opposite of Knuckles who is hot headed). He was the thoughful guy who crafted his plan rather than using the brute force, which he possess, but that is just a tool. He could get annoyed and lash out to his enemies after seeing his plans failing over and over, but was not the guy who lashed ot at the first difficulty or to a bad joke, or to a simple random request.
He was even amused by Sonic's grumpyness, at the point to tease him.
Shadow is hard to deal with and stubborn without being grumpy.
Also I think there are so many grumpy characters around that the trait feels so clichè, we don't need another one (especially one who is not even supposed to be such).
Not everybody need to get upset to this silly level by a simple question.
