So they've already connected and I assume 800 years from now they will continue to be close. Maybe they're more like family now, cousins? She will be very worried for him and probably scold him more like a little sister, to try and make him take better care of himself. She was very happy until a few hundred years ago when she's started spiraling into a dark place. She also usually walks among mortals in human shape so maybe they've taken walks together.

Jesper is essentially god of love, but he has a lot more genuine warmth and positive energy than what Apollo is used to. He's could probably try to make Apollo smile sometimes when they run into each other and persuades hihm to have a meal or a drink with him. He's running a fashion empire as a fake human so they could run into each other there and he'd check in, he worries for fellow gods.