I'll have a go at some of these...
Johnathan
The Chief Apothecary was the wounded lad's mother.A knight and his son journeyed into the wilds, and were set upon by brigands. The knight died of his wounds, but the son was bought back to the town by his retainers. They fetched the Chief Apothecary, who said, "I cannot treat this youth; he is my son." How can this be?
A three-legged stool.What kind of sitting stool can never wobble?
They parted ways at the South Pole, and each traveled "north" in opposite directions.Another knight was travelling with a friend. They parted ways at a certain place. The knight traveled ten miles due north, while the friend also walked due north for five miles. Neither deviated from their course. Yet at day's end, they were fifteen miles apart. How can this be?
Your left elbow.What can you never hold in your left hand?
She was an elf (or a dwarf, or any non-human sentient explorer).In the forest there is a river that humans have never crossed, because they always got eaten by alligators. One day, a clever explorer managed to make it across. Why was she able to do it?
Johnathan