Hi there! I play Hestia and Demeter ([Unknown LJ tag]).
Naturally Demeter and Hecate have history with one another since she aided in Demeter's search for Persephone. I think because of this, plus leading her to Helios, would have really helped in having Demeter liking her after the whole incident was settled.
And for Hestia-- She was the goddess of the hearth and tended to Mount Olympus, mostly sticking there to look after the vast estates. She was very warm and welcoming to people so I can see her doing her best to be kind and affectionate to Hecate whenever they crossed paths.
Also!! I'm planning to app in Phoibe, one of the Titan goddesses. She just happens to be the mother of Hecate's mother so there's history between the two of them. Since she didn't participate in the war, she was also allowed to still be free and, for the rest of her days, mostly focused on looking after her grandchildren like Hecate so--! There's that too.