Who's Tom?

For a couple weeks now, Jacob has been talking about his imaginary friend, Tom. I've asked him who he is, what he looks like, and where he lives. Well, he tells me that he's a boy that 6 yrs. old, has straight black hair, and lives in Arkansas.

Jacob uses Lauryn's little baby toy and pretends that it's a phone and calls him and says, "Hi, Tom, wanna come over and have a play date?" When he gets off the "phone" he tells me that he can't come over because he's sick. I've been thinking about why he created Tom because Spencer never did anything like this. I've noticed that he brings Tom up a lot while Spencer is at school and calls him his "brother" and when he's playing with other friends, Tom is never mentioned, so I think Tom is replacing Spencer. Jacob just absolutely adores his big brother and I guess he's pretty lonely when Spenc is gone. It's actually pretty sweet.