So, I've said it many times, I used to LOVE HoO when I first started reading it (ignoring the first book, extremely boring introduction of new characters). But when I finished that and ToA, my rating of the three series became: PJO>ToA>HoO. Here's why:
(I'll start with Kronos first, because, well, first series.)
Kronos
- Is greatly feared
- Titan of Time, supposedly super powerful
- Even Gods partake in battles
- Manipulated and possessed Luke while still reforming
- Seemed like an actual threat throughout, torturing demigods in sleep, turning them against each other, actually scared the Demigods
- Has a risky plan which depends majorly on Demigods' choices but still gambles his way to success (ALMOST).
- Wouldn't have been defeated if Luke didn't sacrifice himself.
Gaia
- Is greatly feared
- The Earth itself, supposedly almighty
- Gods terrified but refuse to do much, don't care
- Tried best to put Demigods in a tough situation to betray each other, fails
- Barely appears in the series but has a past with almost every character who appears, just says a few lines and fades away and gets insulted every few pages
- Has a strong plan and backups for everything but all the backups fail one by one; very commendable, intricate and villainous plans nevertheless
- Literally got put to sleep minutes after waking up and was obliterated with fire
This may seem heavily biased, but while Gaia had really good plans against the Gods and the Demigods, she fails miserably. Kronos having plans which even the readers could possibly find flaws in, still stays a constant threat and a cause of fear; unlike Gaia who is basically given new nicknames every time she appears.
There are a few reason to this (according to me):-
#Contradiction doesn't necessarily mean an opposing point here, it is to show HoO's storyline.
Percy and other Demigods were relatively younger, and the series was a first person narrative by Percy. That affects his POV a lot. Contradiction: HoO also has young characters who have POVs and have been portrayed as PTSD survivors, which they are, but which also takes away several of the elements of expression about the main challenge.
Kronos is a clear mastermind throughout and everyone is aware of him. His plans are closely followed and neutralised with various efforts, although a lot of it is sheer luck. Contradiction: Gaia is also a clear mastermind, however she works more silently, causing her plans to be comparatively more unpredictable. Despite having this advantage, her traps are guessed and neutralised with more ease as compared to Kronos' masterplan. This could be because most of the counters to Gaia's evil plans were convincing the Gods to not be idiots.
Kronos receives a lot of inside help, having successfully turned a few Demigods over to his side by manipulation and other fear. His plans thus seem to be more fruitful, albeit being foiled by the Demigods. Most of it being "saved by the bell." Contradiction: Gaia, while does not get much inside help, has been plotting for far longer than Kronos and her plans depend entirely on Greeks V/S Romans. If only they had joined hands a bit earlier, Gaia wouldn't have ever woken up. Even though her plans had great potential to be fruitful due to the unlikeliness of Greek-Roman bonding, she fails because of actual strong force and efforts against her, despite having Giants at her disposal and the lack of much divine help.
Kronos is finally stopped when Luke makes a tough choice and sacrifices himself. His powerful time control and army were near-undefeatable without that. Contradiction: Gaia wakes up slowly, gets caught (THE EARTH'S MANIFESTATION?!?!), put back to sleep and blown to oblivion.
That being said, I did like Gaia's indeginous ploy against the Gods. It was nearly successful because of the ignorance of the Gods, but well, you know the story. (Read HoO if not)
On the other hand, Kronos had straight-forward traps against the Gods, who HAD to participate in defeating him to have a chance to survive. Although this can be termed as a mere coincidence of prophecy, it also shows how Kronos was a much more feared threat.
The Demigods in HoO also had various unprecedented buffs, which takes away a lot of struggle which PJO Demigods faced. I mean, how often do you manage to stand your own against Khione by bringing a metal dragon to life? How often do you blow up primordials with white-hot fire?
Wastage of Characters and Potential
Both the series obviously had some extent of unused potential. However, Percy's potential is explored to a very large scale in PJO. Being a first person narrative, this is very helpful to the series and how the readers perceive everything. Most Demigods who were introduced in the series had more than one appearances and spheres of importance.
HoO does not have such engaging struggles to read. It deals with traumatic backstories and vengeful Demigods with random extremely uncommon buffs like Leo having robust pyrokinesis, Piper having miraculous charmspeak, Frank being able to shapeshift albeit having his life tied to a piece of wood, etc. It also has several characters which do not reappear (majority) and are used strictly in their own areas of requirements, which seems to unnecessarily stretch the books.
HoO villains (also ToA) fail to use the Ophiotaurus Bessie to their advantage. PJO had some use of this and basically introduced us to the possibility of how Gods could be brought down with the slaughter of one creature.
Octavian's presence is also wasted in fueling rivalry amongst the Greeks and the Romans, while he could have played double sides and could either have supported evil or betrayed it. He is portrayed more as a nuisance and a repulsive character, who is either not cared about or is openly hated upon.
Biased Analysis
The bias towards PJO credits itself to Percy, the narrator, being a fresh Demigod. This is clearly a beginning of a new struggle and is much more hooking and immersive than HoO. HoO uses several characters' POVs and to some extent, fails to appeal to many of the readers due to one simple fact: They all majorly deal with their backstories instead of actually facing the danger on-hand. Gaia takes full advantage of this, but it seems severely weak, considering how their life is put to risk largely towards the end of the series, unlike Kronos who constantly causes deathly plans to unfold for the Demigods.
The Conclusion of My Opinion/TLDR
And that is why I believe Gaia was an extremely strong opponent, but Kronos was a greater threat. The portrayal of both the villains was odd, but Kronos' evilness and antagonism is much stronger than that of Gaia, who is taken lightly. The credit for this heavily goes to Leo's, Piper's and other Demigods' jokes in HoO; while the trio in PJO majorly maintains a serious tone when the story shifts to Gods V/S Kronos. This is because they face more life threats than being reminded of past traumatic events and being forced to confront their PTSD.
Do ask me any questions/share your opinions!