Miraculous Episode 12 Spoilers
I know everyone is annoyed that this is going to be our only time seeing Luka because the creator's pattern of building up characters for weeks or months and only showing them one episode then they seemingly disappear from the universe. But let's talk about that, specifically how did their episode end.
If you remember Lila's episode ending with the "Marinette, we'll never be friends." And she was also on bad terms with Adrien. And she walked away.
Kagami: Her episode ended with her saying she respected Adrien as her rival and sparked the "So you like Mari?" Thing even tho they weren't close. And she walked away.
So what's the difference between our past love rivals and Luka? Luka was actually kind to everyone, understanding, didn't get in the way, and was genuinely worried when his mom was akumatized and he was not akumatized that's a big thing. He wasn't, he witnessed it. The 2 I mentioned before were one time villains and there isn't any reason for them to be akumatized again so there's no reason for them to come back unless they decide that Lila did actually join the class.
Luka is the sibling of a main(ish) character and is similar age. And my main point. It ended with him on great terms with both of them and he didn't walk away. It ended with him shaking hands with Adrien and Marinette and watching the loves of her life all very close. In conclusion, if the creators aren't dicks, we'll see our emo bi boy again