I want the single most entertaining vtuber possible; the model is irrelevant. The catch has to be that they're also suicidal and clearly one bad day away from ending it. Every stream is hugely popular and this tuber makes a lot of money... but you can always tell they end in a depressing, mildly threatening way that ensures no one is certain if they'll ever stream again.
People try to figure out who this person is and get them real help but they never succeed. A month might even go by, leading everyone in their community to panic and assume the worse... only to return one day.
Then, after maybe a year, that's it. The candle burns out. There's no concrete evidence that they actually took their life, but they never show up again... and everyone always just kind of wonders...
I love that internet mystery shit. You know, like the cat girl from Planet Dolan.