In the Invincible comics, Rex survives. The character's fate takes different turns, but death isn't one of them. The storyline keeps him involved and active throughout.
Allen doesn't die. The creators of Invincible comics have kept him alive to drive the story forward and engage the readers with his ongoing adventures.
In the Invincible comics, Amber goes through a series of events that shape her character. She might get involved in conflicts or have relationships that impact her. It's a complex storyline with many twists and turns for her.
In the comics, Mark doesn't date Amber. The storylines mainly revolve around their teamwork and facing challenges together rather than romantic involvements.
Well, in some comics, the invincible characters might die if it serves a greater narrative purpose or to shock the readers. But in others, they might always remain unbeatable. It really varies.