I've realised something quite cool, which is that cats (and maybe other pets as well) can get angry at death for taking away a loved one. This may result in death actually giving that person back! I discovered this accidentally when my sim died of unnatural causes, and my cat berated death, only to get my sim back. I don't know whether it would work in a different set of circumstances, but I thought it was quite helpful. Also, if anyone could help me with how to adopt a unicorn, that would be great. I have over three BFFs, including the unicorn itself, but every time I try to adopt it it comes out with the whole "Prove to me you are a friend of all creatures" spiel.
Hope my tip helps, and that someone helps me!