Never work with kids or animals.
Kids and animals are crowd-pleasers and scene-stealers, which is why the curmudgeonly comedian reportedly hated working with them. Too much competition. Not to mention that writing believable kids and animals isn’t easy. But if you’re looking to evoke poignancy or brighten up a dull scene or give your hero some instant likability (or your villain instant despicability) you can always add, as they say in Shakespeare in Love, “a bit with a dog.”
Try writing a scene with your protagonist or your villain interacting with kids, animals, or for a real challenge, kids and animals.
A hint: Make it subtle.