This is not suggestions because Pathfinder already made choices about investigators and foxes.
Foxes. When I get a gaming group together again, foxes will have cleverness. They will have an extra 1-4 tricks per time they get the feat. Animal companions and familiars can possibly get this as a feat. In any case, opening doors, defeating tracking, ect are all tricks a fox or cat might learn. They will also have no fly and +4 stealth.
Detective. I am working on a detective base class. If anyone wants to post or link what they have already, great. I’m thinking good will save, ok reflex, and poor fort. No slight of hand or sneak attack. Add all knowledges as class skills, unarmed strike, and stunning blow.
2nd level Evasion and Reconstruct. Reconstruct lets the detective do a legend lore on previous events. Each successful search and spot for evidence by anybody gives +5 per Detective level to the chance to trigger this. It's an extraordinary ability that cannot be dispelled but it takes a full minute.
Evidence. Doesn't have to be valuable. It can be leftover spell components, claw marks on bone shards, ect.
Ring of Truth could teleport away when Remove Curse is cast opon it.
Cleverness could be a feat or ability that familiars get at certain level or hit dice.
Once gained this allows access to other abilities or feats, such as sense astral or reconstruct.
Foxes like most animals have far superior sense of smell and hearing than humans, and like most animals in my view should get +2 to +6 depending on the situation.
A weapon of returning, after it hits or misses, will magically reappear in the thrower's hand. It goes through the 5th dimension, a space between parallel timelines.