There is something that has been on my mind for a long time. As seen in the movie, Nigel stuffs dead animals and examines them. He seems to have these strange obsessions. But he seems to be very gentle with his dog. This got me thinking, what is the difference he feels towards other animals and his dog? Would he do the same things to his dog if dog were dead?
So I had this ask set aside while I pondered my response...and then I forgot about it in the chaos of daily life. But we're back to it now, and I'll do my best to give a coherent answer. Hold on to your seat, this is going to get a bit weird.
There is, in my mind, no difference between the tenderness he shows towards Luther and the care with which he preserves the dead animals in his collection. Remember the beginning of the movie, when Alex is snooping, and Nigel checks his trunk to make sure everything is okay, and he oh so gently pets his stuffed cat. That's the same emotion we see him show to Luther (who is actually the neighbor's dog, not his.) He loves and cherishes the creatures around him whether they are alive or dead.
If Luther died, I have no doubt Nigel would attempt to preserve him too. Even the fact that Luther isn't HIS dog lends itself to this picture of Nigel as someone who cares for animals--there's no familial obligation there as you might have with your own pet (or the one your parents picked out, more likely). His attachment to Luther suggests other things, too--that perhaps he longs for something to love and to love him unconditionally. John Colbie seems like the kind of guy who would absolutely refuse to get a pet. His anger at Luther's barking suggests it would be a terrible idea, even if we didn't already know he has a short temper and mistreats his own *human* family members. Heaven help an animal living in that house who was too loud or inconvenient at the wrong time. Now apply that same principle to Nigel, and feel your own heart breaking in your chest.
Many people tend to view taxidermy and related activities as weird, gross, and upsetting, and this attitude stems from our relationship with death. Society teaches us that death is bad and frightening and that dead things are unclean and taboo. The WHY of all this is extremely complicated and beyond my ability to explain here and now, but if you want to get into a super crazy academic deep dive, check out Julia Kristeva's Powers of Horror: An Essay on Abjection. The abject is a concept that figures heavily in Gothic and horror narratives, and it very much manifests in several ways in this movie (itself a Gothic narrative).
All that said, the main point here is that dead things make most people deeply uncomfortable. Nigel does not find death fearful or disgusting and therefore dead things do not evoke revulsion in him. Just the opposite, I think. Alex remarks on Nigel's "fascination" with death and dead things. Nigel sees death as something to investigate, interrogate, and in end, even embrace. Death does not stop him from feeling affection for his creatures, and the reverse is also true: affection does not stop him from seeking out or embracing death, for others and for himself. Nigel is fully capable of deeply loving something and killing it just the same...as Helen could attest.
