One of the most heartbreaking characters in the Marvel universe is X-Men's own Sentry. This revelation came in the one-shot Sentry: Fallen Sun. The issue was written by Paul Jenkins and illustrated by Tom Raney.
Fallen Sun was an epilogue not just for the crossover event Siege but the entire Dark Reign storyline. Following the events of Secret Invasion, Norman Osborn became top cop in the Marvel universe. He established his own Dark Avengers, of which Sentry was a part. Osborn also orchestrated a series of events so that he could attack Asgard, which was located in Oklahoma at the time. The real Avengers showed up to stop him, but Osborn lost control of Sentry and the Void, Sentry's darker half, needed to be stopped. Sentry is capable of taking on Galactus, so his losing control required a harsh response.
Sentry was killed during the battle, and during his funeral, various characters gave eulogies about him. Rogue reflected on how Sentry was there for her at a time of her life when she was unable to engage in physical in everyone but Sentry. He would hug her and that would mean a lot since she couldn't touch anyone else. Even though he's super strong, Sentry does have a softer side as seen when he calms Hulk down by his mere presence. Fans could even go so far as to infer that Sentry and Rogue were possibly in a romance. Rogue's powers often hurt her partners like Gambit, so there is a certain appeal to someone immune to her effects like Sentry.
To make matters worse, Sentry is a forgotten hero. Due to Mastermind’s meddling, everybody forgot their memories of him for a long time. This meant that at the saddest time in Rogue's life she actually had somebody to make her just a little bit happy, only problem was she didn't know that at the time because she couldn't form memories of Sentry. If the saying goes it's better to have loved and lost than never to have loved it all, then Rogue somehow managed to do both of those things.
Fallen Sun, which is a play on the one-shot focused on Captain America's death titled Fallen Son, is interesting. It has characters like Rogue, people who fans wouldn't think of having interacted with Sentry in the past, inserting themselves in the character's history. It goes to the meta heart of Sentry's purpose, which is rewriting the history of the Marvel universe, and nowhere is that more tragic than with Rogue.
