So , I re-read the comic to catch clues and make a theory and I came up with something like this . So we know that according to Episode 19 , Lumine 's cute wolf pup (mistaken for puppy form) isn't his real form . It also explains why he was surprised when he transformed he was surprised and he says I quote , " I completely forgot about this!! , Why can't I transform normally " At first , I thought he meant he could not transform like others but skip to Episode 19 he says , " It's been over three months and I still haven't be able to transform normally . "
Three months . In first Episode , Hageman says , " You've been causing trouble for past two months !! "
So, before that something has happened to him . Maybe his full form is his wolf form .Also in Episode 5 , Lumine has a pendant and he looks sadly into it . I think he is searching for his lost father , trying to find clues about him .
In Episode 6 ,there was a flashback scene with Lumine begging his father not to leave him alone . It seems he was a very small child ( based on the hand size ) . His father refuses saying he has work . Lumine begs him to let him come with him but he refuses .And the final lines are
Don't leave me alone .
This would explain why he had come to the city , to search for his lost father .
Also in Episode 6 ,When Kody throws a wolf toy ,Lumine asks wheither he like wolves . He says he likes bunnies . He also says ," I think wolves are cool too though .. But I see them more as siblings .. "
Also most important clue is in the description :
A runaway werewolf, Lumine, meets a witch boy named Kody and is being hired to work as his bodyguard. Lumine, being determined to befriend Kody, tries everything to get Kody to trust him, while Kody tries to keep Lumine away from him. Their life gets even more complicated after an unfortunate event that leaves them to try to survive on their own.
So, based on the last line " Unfortunate event that leaves them to try to survive on their own " Meaning something would happen . Mostly I think it would be Kody getting kidnapped because in Episode 17 it is mentioned Witch children aged 9- 15 are disappearing .
I need to re-read the whole comic once again to make even better theories but for now these are my thoughts .