Ironman and Captain America have died in the comics. These deaths usually come with intense story developments and can sometimes be reversed or have lingering effects on the overall comic narrative. It all depends on the specific comic series and creative direction.
Well, it's a bit complex. Captain Marvel died in the comics due to a combination of factors like facing an extremely powerful villain and getting caught in a situation where she couldn't escape unscathed. Sometimes, it was also due to sacrifices she made to save others or the universe.
Captain America's death in comics was a complex event. He was assassinated by a sniper's bullet, but the circumstances leading up to it were filled with political intrigue and superhero drama.
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.
Rex Splode remains alive throughout the comics. The storylines don't feature his death. Maybe there were some close calls or dangerous situations, but he survived them all.
A great Captain Rex fanfic should have a strong understanding of his character. It should show his loyalty to the Republic and his brothers. For example, it might depict him leading his troops bravely in battle.