In that case, maybe Giles witnessed someone else calling on her to solve a problem-- maybe fairly early into his return to the Daybreak side of things, when his acquaintances were more mixed-- so he doesn't owe her anything, but there's the potential to make a deal if a game situation ever gets desperate enough. This is all terribly vague, but that way he could know her by reputation and she could recognize him as an acquaintance witch, which is something to start from. It could be interesting to get him tangled up in a favor to her, down the line.