
I have read a few in choiCale fanfics in Ao3 but yes,I do notice majority of the readers ship AlbeCale,we all simps for that dongsaeng-hyungnim relationship and also probably because it's canon that it is only to each other that they show their true face.
ChoiCale is also cute! But most fans probably see them more as a Uncle-nephew (since you're still reading the novel you'll get to that point!><)
But yes!Slight spoiler, Cale does know how old Choi Han is, and in the later chapters Cale tells Alberu, as of now I think they are the only humans who are aware of Choi Han's real age (not sure about the dragons)

Ah i see( ̄∇ ̄") yea i read on ao3 most of it are either white star x cale or albecale (=・ω・=) idk yet who is white star do i dont read WS x cale but yeah, i ship albecale even before i read novel ╮( ̄▽ ̄)╭ but i still kinda ship Choicale before but didnt found much fanfic abt them so this explain it. Well abt uncle-nephew relationship, i guess i get what ur saying(づ ̄ ³ ̄)づ but i still kinda ship them cause its kinda cute>.<
their ages incase some manhwa only readers missed it or are unaware:
Cale = our hot handsome smart mc is currently 18 years old
Lock = our cute wolf boy is 13 years old
Choi Han = our original cute strong mc is 60+ years old although his outer appearance looks really young (This is not a spoiler, it's mentioned in the first chapter of the manhwa that he spent DECADES inside the forest of darkness, so yes, our Choi Han is older than Ron aka Cale's butler. The reason for his young outer appearance or his slow aging is explained in the novel)
Rosalyn = our smart Rosalyn is currently 22 years old
Black Dragon =Since our best boy's name hasn't been revealed yet, imma stick to calling him black dragon for now. Our great and mighty dragon is currently 4 years old
On and Hong = Our cute siblings from the cat tribe are 10 and 7 years old respectively.
Alberu = ahhhh the sun of the roan kingdom! Our guy Alberu is currently 23 years old