There’s many ways to go, it could be a book with a similar vibe, similar character, or story/arc/plot…
There’s:
Uk with his underdog to most powerful character journey.
Mu-deok, with her do anything to survive journey.
Yul’s slight corruption and redemption arc.
There’s the romance between Uk+Mudeok/Buyeon.
The magic/energy power system, or the setting of a school of mages.
Different powerful families competing for power whilst trying to avoid war.
I have one suggestion but if you lot have any. write them below please!
My suggestion: A Darker Shade Of Magic – I only just realise how similar of a vibe this series has, especially the first book! You have Kell, with no parents given a big job to do for the Royal family, as he uses his rare magic to complete quests etc., Lila, a street smart girl just trying to survive amongst the rough world shes stuck in. You have Holland who’s sort of a grey character, not alike any character in AOS, but he has a parallel journey to the first two and they sort of give of a Uk, Mudeok + Crown Prince vibe.
by Acrobatic_Rain_1346