It might sound kind of lame, and I will be totally cool if it gets a no, but I was thinking of something like the ghost of a lost pet lingering around it's former human. And when the human is given the sight they kind of get their pet back. Or maybe, in a just as corny fashion, a kind of animal spirit who would have acted as a totem and then becomes more of a companion. 

Essentially what I am asking are these two things: Can my character have a spirit pet? And can it be a tarantula/big spider?