My school had a lot of chill subs, including the former elementary music teacher. She sadly retired after being diagnosed with Parkinson's Disease, but decided to stay on as a sub.
My history teacher, however, was the exception to the rule. Her go-to sub was a miserable killjoy bastard who clearly took the job solely for the power trip. He was pretty much the real-life equivalent of the grumpy old neighbor who takes your ball away after it lands in his yard.