Toy Agression

Question
I live in a house with 4 people, and one Jack Russell Terrier. He has a favorite toy mouse that he loves to have thrown for fetch...but one person in our house can get close to it. We have no other problems but this one with is toy. Also when that one person is home he tends to ignore basic commands from the rest of us. We all share equal responsibility for him, but he loves one person more than the rest of us!

What should we do?

Answer
The JRT is a "one person" dog, the more independent the individual dog is, the more this applies.  Your JRT is resource guarding with that mouse.  This is not a retriever, this is a breed designed to go to ground after animals much larger and fiercer than they are.  Tenacity is a prized behavior in the JRT.  This isn't about "love", this is about rank.  That one individual is most likely seen as the overall higher ranking vis a vis dog and human(s) in your household.  There's not much you can do to raise the rank of three humans as a group, but individually you can all ignore the dog (actively ignore) one by one over the course of each day for 30 minutes a piece.  Because so many are involved, this might take some time.  Higher ranking individuals are not freely approachable, but this is more a privilege designed for the most high ranking (or alpha).  By ignoring the dog actively, you will be elevating your rank somewhat, but you can not take the place of the dog's perceived alpha.  As for any dog ignoring any command, if the dog has been trained with positive reinforcement, and has a solid 100% response to trained behaviors, he will never ignore a "command".  Your dog needs to go back into training with positive reinforcement only, because he is not trained.  You can use the mouse as part of the reward by withholding it for a while and then using it during the training process (much like objects are used in the training of service dogs), but do this sparingly and only after the dog has obtained an understanding of the behavior you are training.  Do NOT chase or go after the dog to retrieve the mouse.  Use it once in each training event, at the end (after real reward.)  The JRT is, again, not a retriever.  Chasing after the dog only erodes his perception of your rank, as well as setting him up for a possible aggression problem (mostly fear.)  Owning a dog isn't a popularity contest.  Each person in the household can have his or her own relationship with the dog and each should learn, and utilize, the same training methodology.