Grunge is basically a label for any rebellious music that came out of the Seattle scene - Nirvana is essentially punk influenced along with some rock and roll classics and Kurt Cobain confirmed that - Pearl Jam is harder to define and Alice in Chains is definitely metal, labeling them just as grunge is demeaning.
Whoever fights monsters should see to it that in the process he does not become a monster. And if you gaze long enough into an abyss, the abyss will gaze back into you