I liked the show well enough (watched it up through s5 or so), but it never really hooked me while it was airing.
Then one I day I happened to rewatch "I Remember You" after having recently finished caring for my Alzheimer's-afflicted grandfather for two of the worst years of my life. Talk about a haymaker to the feels. The specific scene where the Ice King is shooting icicles at the ceiling wailing 'why can't anyone help me?!' was so eerily similar to something my grandfather said in one of his rare moments of self-aware lucidity that I almost broke down on the spot.
I ought to give the show a full rewatch one of these days.