It's a bit complicated. Jean Grey's fate varies depending on the comic storyline and continuity. Sometimes she's dead, but often there are plot devices that bring her back.
One of the best Jean Grey stories is 'The Dark Phoenix Saga'. It's a classic that shows Jean's struggle with the powerful and dangerous Phoenix Force. Her transformation into the Dark Phoenix and the resulting chaos is both thrilling and tragic.
Well, Jean Grey's death in the comics has multiple scenarios. One common cause was her inability to control her immense psychic powers, which led to her demise. Another time, she might have given her life to protect the world or her fellow mutants.
Yes. The circumstances surrounding Jean Grey killing Cyclops in the comics are quite dramatic and have significant implications for the story and other characters.
Love and relationships also play a big role. It could be a romantic relationship between characters from both universes or just friendships that form across the boundaries. There can be a theme of adaptation too. How would a character from one universe adapt to the rules and culture of the other? For example, how would a Twilight vampire deal with the presence of mutants like Jean Grey who have such different powers and ethics. And often, there's a theme of power struggle, as both universes have characters with different levels of power and influence.