I don't know if you knew this already, but Bob's (Iapetus') son was Atlas, and Atlas' daughter was Zöe. This means that she is Bob's granddaughter. When she died, Artemis turned her into a new constellation. Now, with all of this in mind, remember what Bob told Percy? "Tell the stars I said hello".
Guys.
He was asking Percy to say hello to Zöe for him.
If that's not heartmelting, I don't know what is.