Actually not so much fascinating but rather mundane. Both were in the snow.
The first time I went for a hike without checking the weather. I had a topo and compass but not a GPS (which I almost never carry anyway) and, as it was a day hike, no stove or any overnight supplies beyond a bottle of water. In the summer that's not really a problem (you can almost always survive overnight in summer without a problem even with no preparation, food or equipment, especially if it's not raining) but stupid and dangerous in the winter at altitude. I was wearing relatively lightweight "travel" gear because I expected to be sweating, not sitting still. In any case it began to snow heavily and I could not see any landmarks, much less my map. I tried dead reckoning to the trailhead but eventually came across my own snowshoe tracks as it began to become dark. Very scary. I was also frightened of stumbling into a lake or off a cliff, both which were relatively nearby. At some point the dog became fed up with my antics and just walked away, which he normally never does. Lacking any better plan I followed him and he walked pretty directly to the trailhead which turned out not to be that far away.
The second was much more serious: again, I got a late start because of work and got into the wilderness around dark, not having checked the weather. I skied a bit but it's dangerous to travel at night, especially in the snow. I do have a special lightweight and compact rig I developed for sleeping below zero, but it requires some time and attention to set up. So I put up a tent (least I had brought one!) for me and the dog because I wanted out of the weather and was too tired to try to make a robust shelter, especially in the dark. Unfortunately the spot I chose was exposed and the winds were quite strong, pulling branches down and threatening to pull the tent (I had only anchored it to the snow). In the dark I had to get up, find a tree well, and dig a hole. I put my skis and my pack over the hole, dug a chair, and then spent a sleepless night with my dog. I opened his jacket and my jacket, sat on the dog pad and my sleeping pad, and wrapped my sleeping blanket around us with the dog blanket over the top. I put the dog's jacket under him. He sat up/stood up all night and kept me warm (most of the time I was hugging him). I was afraid to fall asleep and potentially freeze to death because the covering required continuous adjustment. When we dug out in the morning up my tent was gone (I eventually found it) and there were branches that had fallen where it had been, though who knows if they really would have been dangerous? At least it hadn't snowed much, though it was pretty cold.
(One of my students managed to dig a shelter using only his skis when he was caught downhill after skiing out of bounds, but he did the digging before the sun went down, and was rescued in the morning. His ski gear was adequate for overnight in those conditions).
The common thread here is that I was dumb, dumb, dumb and deserved to suffer. I prepare better when writing code than I did on these two trips: I was overconfident that my skills and experience would get me through.
BTW my dog weighed almost 150 lbs (not much less than I do) with legs as long as mine. He had (he's since passed away) well over a thousand trail miles and was trained to stick with me regardless of distractions, which is why it was so shocking when he walked away. He only did that one other time, when a group of us were cutting a trail -- I assume he was bored and went back to camp in the hope of finding forgotten food. Oh yeah, he would also do it sometimes in the office if he thought someone might be eating a sandwich :-).