I know this is "as a player," but I figured I'd throw a quick curveball and see if I can miss a bat or two.
There are times when I run games where I have brief moments of deep empathy or connectivity with an NPC that I'm running. This will either be because (a) something that a player has down through their PC to bring extreme vitality to the situation or (b) I'm framing an initially nebulous scene that I'm having to quickly resolve in my mind in multiple ways (what is going on here? what are the dramatic needs of a/the PCs and how can I test that? what are the dramatic needs of the NPCs so I can advocate for them/provoke the players?). (b) happened a few sessions ago in the Stonetop game I run:
* Players are on a perilous journey through Ferrier's Fen and wanted to make camp.
* A cave in a steep face with signs of intelligent life is discovered.
* Grizzly fiction continued to resolve in my mind and accrete in the fiction as the players explored the cave and we discovered what was there.
* A Fen Troll is chained to the back and its wasting away, terrible wounds where the cuffs for the chains are as well as burns on the pustules. It is clearly not getting enough food or is refusing to eat. It is not violent when approached, but the PC who approached it initially has the ability to placate the monstrosities.
* What if it is unnaturally nonviolent? Why is it so? Why is it chained. Its being kept here by someone who is keeping it alive. It desperately doesn't want to succumb fully but it would rather die than live out this terrible fate. It is a she. I give her (Yoanaw) the
Instinct: To perish rather than succumb to this fate.
* The "caretaker" of the Fen Troll has returned; the growling and yapping wolves of The Blessed (sort of a Druid/Shaman) guarding the mouth of the cave signal that. It is a Fen Walker (basically "one who walks the Fen") who is a mighty huntress with mysterious sorcery and an appendage of that of a great cat, signaling her likeness to the other aberrant creatures that are spilling from the Fen over to The Great Wood (indicating a march of the affliction toward Stonetop). This connects her to the great power of corruption in the frozen (its Winter) bog. She totes a chain gang of frog-like demihuman creatures (in D&D parlance, they are near Bullywugs). She is going to feed them to the Fen Troll? Ok, its her sister. She cares for her. She has cared for her ever since...their mother died in delivery of her sister...a delivery that came with a rot that infected the arm of this mighty huntress...so she had to make a bargain with the great corruptive power of the bog for her life and her arm.
* Ok. What now? They were cast out of the enclave of Fen Walkers when the young girl got sick with Fenblight (it spreads like wildfire as the Fen Trolls shed casually and at-will). They tried to hide it. Radomira (the older sister) took her young, afflicted sibling from the only home they knew. When things got bad, she chained her up in the back of the cave. She kept her distance. She provided her food. For a long time she has looked for a way to cure her sister's curse...but to no avail. They are both hardened and live brutal, rote, hopeless lives at this point.
Radomira's Instinct: To feed and "keep safe" her "former" sister no matter the cost.
For various reasons, the plight of these two sisters bonked me over the head with the emotion stick as they formed in my mind and in our collective fiction from the formless state of the opening of this scene. And as we played out social conflict between each of them and interrogated the truth of the matter I find myself rather immersed in playing both of them and in playing the scenes around this situation.
This happens a fair bit. It happens in every game I run, though not every session. The game that
@niklinna is mentioning above has had more than a few moments like the above for me (as GM). There also were several moments in the Torchbearer 2 game I GMed for him.