I once led a D&D campaign jokingly called "Husband Quest". It was largely inspired by Haunting Ground for the ps2(amazing game btw). I wanted to make the typical evil wizard DnD affair but replace all instances of magic with alchemy!
The campaign was supposed to be shallow and stupid, just a break for me but--as I so often do--I began developing my main antagonist far too much.
The big evil old man, wizard or lich, is such a typical and easy villain. The safe final boss. I wanted him to play his part, of course, but to write I have to breathe that character and interesting...feelings...came up.
He was the last in a long line of academic, you know, the seeking arcane knowledge all powerful types, and his line was long since tasked with solving the mysterious of the universe so it could be conquered.
We (he and I) found ourselves at the end of our lives with nothing much to show for it. Barely a scratch on the surface of what we were looking for, and our forefathers did little better. He thought of how he had no sons, but then, could his own sons do any better? Or would they find themselves where he was now, empty handed and with not much to say?
Would you believe that it was only then, in his old age, did he even begin to consider that he might want something different? That this pursuit of knowledge, the mission of his bloodline, held no appeal to him?
Before the campaign ended, I grew too attached to him and had to bring in a whole other boss/big bad because I didn't want to let him go.
I wanted us to be together for a little longer, until we knew how our story would end.
Have you ever been an old man? At the end of his life with nothing but an empty castle to show for it? Did you get angry? When you realized it was far too late to steer your life in a new direction? What did do you? Did the anger consume you, turning you into a wraith for some adventurer to fight at the end of his journey?
Did you strike out anyway? Leave your castle behind for that silly little DnD party to find, confused by your absence? Did you walk to the edge of the world and howl your resentment into the void?