The only reason Zeus loves Hargaan is probably because he birthed Hargaan himself. I've once read stories that Zeus sometimes transforms into other beings to lure women and I think I read about him birthing a kid himself. In this series, Zeus most likely transfigured into a woman and birthed Hargaan. It would explain Hargaan's extremely close resemblance with Zeus and why Hargaan doesn't have a known mother despite Hargaan clearly remembering she existed and lived with him in Olympus. If he's literally Zeus's clone, I am scared he'll have a change of heart and side with Olympus despite being a just and upright person.