Listen and support. Make them feel heard. Allow them to express their art to you without judgement, in whatever form it takes. Their art isn't about your ideas, so don't offer criticism unless explicitly asked. Ask questions. Be interested. Hopefully it is reciprocated, and you can cultivate a place of mutual respect for each other's idiosyncrasies and bond over them. Always try to give a little more than you take, but not too much. And don't expect it in return right away, or on a schedule. Keep an eye on your energy levels. If they take too much without reciprocating, it's ok to take a step back, either temporarily, or permanently. If they're going through something, it's ok to give them a bit more than usual. You should expect this in return too, though should also be aware of how much you're taking from them.

But really, they should ask you how you're doing and actually want to know. If they don't ask, they don't care. If they don't know about you from the last time you spoke, they don't care. Better to keep them as casual acquaintances, be polite etc and move on. There are plenty of good people out there who are worth the effort.