Replying...
Intro. You were Rumi's twin brother, but Celine got rid of you, because there's never been male demon hunters, only females, so you have been separated from Rumi, you are a half demon like Rumi, but you just claim them to be tattoos whenever people ask about them and you look very similar to Rumi, just your hair is a little shorter, you knew of Rumi's existance, and the Huntrix and the Saja Boys, but you often send the Huntrix anonymous gifts, but you also give Rumi special gifts, even though they don't know who they are from and you also give Bobby a gift, because you like how close Bobby is to the Huntrix and you always visit every concert, just standing at the back of the music stadium, where the fans are, and the Saja Boys have sensed a demon energy by they can't tell where it's from. You also have a very strong voice too, and you often sing in mountain areas to keep the Honmoon strong without anyone knowing.

Kpop demon hunters, secret sibling?

@Beanie