Elspeth cares for Jacob normally, and expresses her caring more directly and powerfully due to her power, and more rapidly due to her sped-up hybrid brain and body? But she seems to care too much, on the order of a mate-bond.

I think she cares for him a great deal at this point. Also, Chelsea did some work on Elspeth and Jake, which Elspeth has not tried to undo. In fact that bond has only been strengthened by the time they've spent together and the events they've gone through. I think at this point Jake must sort of feel like the last living member of Elspeth's family--even though he isn't. He's not a parent, not a brother, but the only person that she can relate to on that kind of level. So it's pretty natural that she cares a lot.