OK I ship this couple because I really think they could be perfect together and balance each other out. Stefan can make Kat more compassionate and once she has someone on her team she may not feel the need to be so me against the world.
Kat could make Stefan lighten up and enjoy life more as well as teach him how to be a stronger vampire. She may even be able to help him overcome his blood addiction by helping him the way she made herself immune to Vervain.