First of all, thanks everyone for the response. Every post was appreciated.
Question: Does your player simply want an animal companion & to be a spontaneous spellcaster, or does she want an animal themed spellcaster?
The former. And it's more for RP and flavour then for anything else - she just likes the idea of hanging around with an animal pet which grows in power with her Sorcerer levels. So, she's going to be a gnome sorcerer riding a tiger as an Animal Companion.
I think I'll go with the modified Fey bloodline, as originally proposed by dthunder, because it's probably the solution with the lesser impact on the official rules. All the other solutions make sense, though. The Animal-themed bloodlines are good, and I also agree on the need for a spontaneous divine caster.
--
Nekomante