Here is a small list of a few minor ideas that I've had while playing DF.
- Without any toys to play with, Dwarven Children will sometimes play with Bins, Barrels, Mechanisms, Stepladders, and some more objects. When they do this, there's a small chance they'll sometimes break them, rendering them as nothing but refuse. Some dwarven children may also injure themselves a bit while playing with these kinds of objects.
- Cats, Kittens, Puppies and other small pets will sometimes sit on bins or barrels, making dwarves have to take them off or wait until they get off to use them.
- Visitors, Liasons, Gorlaks and other passive entities with the "Learns" attribute may sometimes wander through the fortress to learn the location. Alternatively, creatures underground that have the learns tag and are passive may avoid dwarves until they are shown to be passive, where they will then tolerate their presence.
- African Violets - Some dwarves like them for their striking colors. Found in warm grasslands.
- Dwarves that are especially hostile to those who are not like themselves may try to push and attack other life they see in taverns. Dwarves who are protective of life will probably attack said dwarf. Eventually, this may escalate to a brawl.
- Elk Birds and wildlife will try to steal food any dead dwarves were carrying that's not picked up.
- If a Dwarf is suffering from large amounts of stress or a lack of sleep, they might start to hallucinate. They will then do things like relocating items in stockpiles to random spots, grabbing things out of dwarves' hands and then running, destroying furniture, threatening other dwarves to "FEAR ME, OR FACE MY ULTIMATE POWER! AHAHAH!", drinking an excess of food and drink, following random dwarves around, and potentially attacking other dwarves.