A better title would've been "Gypsy and the Asura" (or Gypsy and the angry little indian boy who shoots blue fire from his back)
STORY STUFF (If you're not interested in the story, you can skip it):
So, this picture represents their relationship. Apollo refuses to use the power within himself (because it killed his mum or something like that) and as a result, his Asura powers are weak. Sara has an extremely high amount of energy, but not much fighting capabilities (don't worry, she learns some eventually). Separately, they can be taken out, but together they're unstoppable. She can act as a source of power, but only with skin to skin contact (Neither of them are very comfortable about that fact).
Oh I should mention that Sara can't just link up with anyone, she has to be "compatible" with that person (like, you wouldn't hook up a car battery to power a skyscraper, nor would you use it to power a remote control).