BIOGRAPHY - page 7
Mar-Vell detected something amiss within his own body using his cosmic awareness. He ignored the warning signs for a time until he, Eros and Mentor traveled to Sanctuary II to retrieve the petrified body of Thanos. In a battle with Thanos' remaining worshippers aboard the vessel, Captain Marvel collapsed in a fit of coughing. Mentor and Eros were alerted something was wrong, and so Mar-Vell was forced to confront ISAAC's medical readout confirming what he already knew. On Titan, it was known as the Inner Decay. To the Kree, it was the Blackend. On Earth... cancer.
Captain Marvel struggled to maintain his composure and inner peace in light of the diagnosis. He traced his sickness to a battle with Nitro years earlier, when he had been exposed to the Compound 13 nerve gas. Many of Earth's scientist heroes joined Mentor and ISAAC in trying to treat Mar-Vell, but ran into two roadblocks. The first was the photonic power of his Nega Bands. This unique power had apparently slowed the progress of the cancer for years, but could hold it back no longer. However, the same principles of the Nega Bands that interfered with the cancer now interfered with attempts to cure it. Radiation and other treatments were absorbed by the Bands' protective effects and could not target the cancer cells. The second roadblock was Mar-Vell's Kree heritage. Any medical records regarding treatment of the Blackend were in the possession of the Kree Empire, and the Supreme Intelligence welcomed the death of the traitor Mar-Vell. There would be no assistance from the Kree in saving the life of Captain Marvel.
Mar-Vell was comforted by Elysius when he revealed his sickness to her, but his composure cracked when he contacted Rick Jones. Mar-Vell wanted Rick to get treatment, just in case their 
bond had somehow transferred the sickness when they were linked. Rick was an orphan, though, and could not accept Mar-Vell's death sitting down. In his emotional state, Rick lashed out at Mar-Vell for not fighting more, and they parted on bad terms. Mar-Vell felt even more alone than before with his pain.
Time passed, and no progress was made on a cure. Mar-Vell wore a special tunic conceived by Mentor and ISAAC to slow his deterioration, but he grew weaker with each passing day. Mar-Vell reached out to Eros and asked him to look after Elysius when he was gone. Soon after, Mar-Vell collapsed and was reduced to bed rest. A parade of heroes arrived from Earth to pay their respects to the Protector of the Universe before his passing. Drax the Destroyer came escorting a Skrull ambassador-general. The Skrulls officially honored Captain Mar-Vell as their greatest opponent, bestowing the Royal Skrull Medal of Valor on their valiant foe. Rick Jones finally overcame his feelings as well and reunited with Mar-Vell on his deathbed. The two men, closer than any two could be, spent their final hours together reminiscing about old times.
The time came when Mar-Vell slipped from consciousness the final time, and fell into a coma. As the heroes of two worlds gathered around his bedside, Mar-Vell entered a plane between life and death. Here, the statue of Thanos's corpse became reanimated and approached Mar-Vell on behalf of Mistress Death. Thanos seemingly revitalized Mar-Vell, giving him the chance to die on his feet. Indeed, Mar-Vell fought back and did his best to stop Thanos from delivering the final blow and killing him. Captain Marvel won the battle, but he also accepted it was all naught but an illusion. With Thanos by his side, he accepted the kiss of Mistress Death. As Captain Mar-Vell, hero of Earth and the Kree, moved on into the afterlife side-by-side with his greatest nemesis, Mentor switched off his life support monitors.
Mar-Vell was dead.
[Marvel Graphic Novel #1]