I get Apollo, btu I dont get how Demeter, Hermes, Aphrodite, or Dionysus kids are underpowered let alone could be op like Percy...
So Riordan has Percy as OP and justified by the many domains, titles, and godly abilities of Poseidon. He does NOT do this for the gods I listed. Since you said you can get Apollo, I'm just gonna skip him.
Demeter - Goddess of harvest and the "life" parts of "life and death."
She caused winter and famine via no plant growth, has some authority over animals since she's goddess of agriculture, has cursed someone with insatiable hunger (he ate himself).
Her children growing plants is undervalued, especially when one that's powerful could put things into perpetual bloom or keep anything from living. Or get creative -
Goddess of food has children whose food gives buffs and debuffs
Goddess of life has children that can take it away and give it to someone else
Being "they like and grow plants, they're weaker" only works by ignoring a bulk of her mythology. If Percy can cause earthquakes because Poseidon can, Katie can curse people and the land itself because Demeter can (and that's terrifying as hell).
Hermes - god of travelers, shepherds/cowherds, thieves, wit and cunning, writing and language, commerce, diplomacy, and luck and good fortune
I think I mentioned this in a reblog, but he uses magic and incantations, it falls under his domains of writing and communication. Magic alone could make any of his children OP, but he's also a psychopomp (takes the dead to the underworld), god of mediation (because he's god of communication and commerce), AND god of BOUNDARIES - the latter has so much potential, from making and weaponizing barriers, but also negating them.
In theory, nothing could stop a child of Hermes from poofing themselves into places they want to go to, making portals to bring an entire army into Camp Half-Blood, or make a barrier that keeps everyone out (yes, I'm talking about Luke - he deserved to be over powered and on par with Percy by virtue of being the primary antagonist).
Aphrodite - goddess of love, beauty, and sexuality
Again, I made a post about her and Riordan's treatment of her and her children. She's legit one of the most dreaded gods by the Olympians because her power over love has authority over anyone that isn't asexual or aromantic. Plus, Aphrodite Areia, her war goddess aspect, exists.
And even ignoring that, Aphrodite is beauty and it can be found in anything, it's a major aspect of her attraction to Ares (not just him being physically attractive, but because his carnage is beautiful in its own right). Beauty in war, strength and physical power, combat and bladework, you get my point.
Any of her children could be an OP warrior like Malenia from Elden Ring (her bladework is described as beautiful, she herself is beautiful IMO, and she hits harder than a freight truck) or amass such warrior loyalists like Miquella (charmspeak, people, it is OP on its own and Riordan ignores that).
And now, to my favorite to talk about:
Dionysus - god of wine, theater, festivity, madness, religious ecstasy (visions and propechy), orchards/fruit, wildlife, and death and rebirth.
Not even discussing his conquest of India while drunk off his ass, an OP child of Dionysus could, in theory:
Cause mass hallucinations and madness not just in large groups, but over an entire town/city/country
Be nigh-invulnerable with ressurective immortality or be Kenny Mccormick and keep being reborn, memories and all
Potentially have authority over lightning and thunder (The Bacchae) or be loud enough to create something akin to thunder
Inspire loyalty and have the following of a group similar to Dionysus with his maenads and the thiasus (his retinue)
Have a loyal following of MONSTERS in the form of kobaloi (well, sprites - but I feel like in the Riordanverse they would be treated as monsters)
Be able to grant superhuman strength to their followers (maenads, just maenads, they're terrifying)
Lowkey effect the world around them through theater (and madness/religious ecstacy). Imagine a dramatic ass theater kid that embodies main character syndrome and borders on a reality warper (and this is a further justified idea because in Ophic Hymns, Dionysus is kinda an aspect of Phanes - it's complicated, Zeus ate Phanes and Dionysus is twice born among other things)
There's such cool things that could be done with any of the gods, but them and their kids are downplayed because let's be honest, Percy would not be viewed as so powerful if they weren't underpowered.
Tangent time, but in what world would a child of Hecate be weak in any sense? Alabaster should be able to body the camp via magic and Mist.
Or a child of Nemesis, a goddess feared by even Zeus, not being able to control retribution and luck in their favor to never lose. Ethan should be out here winning until he gets hit with divine intervention and even that shouldn't stop his pursuit - because that is a major trait of Nemesis, retribution is an unstoppable force!
Or a child of Hypnos, why is Clovis among those deemed weak when he legit can put anyone to sleep (and sleep is so close to death in mythology that they were born together, he could make people sleep so heavily that they look dead - AND Hypnos is "easily embraced," imagine Clovis having a form of charmspeak where people he puts to sleep do whatever he wants like he's a necromancer controlling the dead).
POTENTIAL WASTED!
Like, even Percy and his OPness is wasted - prophecy was once Poseidon's domain, strategy was once his domain, he used to be god of the underworld AND top god (Mycenaean - it's also where his Earth-Shaker epithet comes from). Riordan didn't even truly emphasize everything would make a child of Poseidon powerful.
Edit
You gotta give me time to type...
