BIOGRAPHY
The history of Forget-Me-Not remains a mystery, with only his first name being revealed as Xabi. Additionally, the nature of his powers, making anyone who was not looking at him directly to instantly forget him, makes it difficult to place exactly when he joined the X-Men or how. Presumably, he was offered membership by Professor Xavier, as he was the only person who knew of his existence through an hourly psychic reminder placed upon himself.
At the point that he revealed himself, it was to a young woman who was attempting to break into the X-Men’s mansion. She was in the process of being devoured by the security barrier, so Xabi attempted to calm her down to slow the process by talking about himself. He claimed to have been on the X-Men for six years and explained how his powers worked to the young woman, who it turns out was a scarred, abuse victim who was a fan of the X-Men. Feeling bad about her situation, Xabi resolved to help her by distracting her with a story.
The furthest back into the X-Men’s adventures that Xabi definitively participated was their Utopia era, when they lived on the raised remains of Asteroid M in the Pacific Ocean off the coast of San Francisco. During this time period, the omega mutant son of Xavier, Legion, warped reality into the Age of X, convincing all mutants on the island that they were part of a perpetual siege on their home of Fortress X. The human forces assaulted the Fortress daily and Forget-Me-Not’s powers allowed him to walk upon the battlefield, unnoticed and unable to be targeted by their weapons. Xabi loved the thrill of the daily battles and knew that, if he ever fell in the field, Legacy (that reality’s version of Rogue) would find and absorb his memories into herself as a living mutant memorial. This moment of forever being remembered was why he fought so hard, as being noticed was his greatest desire.
One day, he was knocked out and woke up that night to stumble upon a wounded human soldier on his way back to the Fortress. The man freaked out, as he believed all mutants were monsters, and was surprised when Xabi treated his wound with antibiotics. The man did not believe he would last until morning and begged Xabi to stay with him until he was gone. The man seemed delusional with his inability to recognize his own name and his belief that he would soon disappear… but that is precisely what happened as the dawn broke.
With the knowledge that they were living in some sort of altered reality, Forget-Me-Not attempted to relay this information to the leader of Fortress X, Magneto, who of course did not remember him. Perhaps his insistence to Magneto to check outside the barrier to figure out what their situation truly entailed subconsciously influenced his actions, or perhaps not. Xabi continued to walk the battlefield and help the wounded soldiers in their last moments, realizing that, even if he couldn’t save the day or leave a lasting mark, he could change things for the better in little ways. Eventually, the X-Men solved the mystery of the Age of X and the world returned to normal. Some of the mutants chose to have their memories of their time at the Fortress erased but others chose to keep them. Of course, Xabi belonged to the latter group, having made some treasured memories.
The number of additional missions that Forget-Me-Not participated in is unclear but he implied that, many a time that the X-Men “caught a lucky break” (by glitches in the system or a secret 
lair’s door popping open), it was actually his presence that allowed the team to win the day. When the X-Men formed a Schism, Xabi chose to travel back to Westchester with Wolverine’s faction to reform the school as the Jean Grey Institute. Xabi took it especially hard when Professor Xavier was killed during the conflict between the X-Men and the Avengers, as the only man to truly know of his existence was now gone. He developed a bit of depression over this nearly complete state of non-existence and started looking into ways to remove his powers. What he settled on was Weapon Omega, a mutant with the ability to absorb the abilities of other mutants, who had recently come into the X-Men’s orbit along with his friend and fellow power copier Mimic. Forget-Me-Not traveled in search of the pair, determined for Weapon Omega to either take his power or kill him, as Xabi did not care either way at this point.
He found the pair helping clean up the destruction from a recent hurricane. Xabi convinced them about his power and his seriousness of taking it away, even if there was a chance of death. However, he did express trepidation of inflicting his curse upon them. This was where the other two men differed in their views of his power, as they believed that the power of not being noticed meant that they could help so many more people, regular people which they thought the big super-heroes tended to forget about in their war with gods and monsters. However, at this moment, the trio’s conversation was interrupted by the sudden appearance of Cyclops and his faction of more militant mutants, looking to recruit Weapon Omega and Mimic. A fight broke out but Xabi was able to resolve it peaceably by having the two power mimics temporarily take his power, making the X-Men forget why they were even there in the first place. Weapon Omega agreed to take his power but asked if Xabi wanted to really think about such a big change. Xabi did have some second thoughts and, while he pondered his decision, the two other men forgot about him and flew away.
Forget-Me-Not went back to the Institute with a new resolve to use his gift to do something that mattered. Some time later, he realized that his chance had finally come. He switched places with the trapped teenager, freeing her from being subsumed into the protective field. She cried out that 
he shouldn’t sacrifice himself for someone so useless but he explained that she should go out and do something that mattered with her life, despite what people might think about her scarred face. The youth was truly touched by his words and actions and promised not to forget him. However, as soon as she turned to go find help for him, she felt that she had just forgotten something important. Fortunately, the suicidal-like mentality that she had started with had faded subconsciously and, upon talking to her mother on the phone, she knew that she was going to be fine. [X-Men Legacy (1st series) #300]
Forget-Me-Not did not die after taking the young woman’s place. Rather, he next found himself abducted by a new team of X-Force run by Cable. The team had him trapped on a flying heli-carrier, so despite his continued ability to escape the notice of X-Force, he could not leave their base. Meanwhile, resident genius Doctor Nemesis had created a video, explaining that they needed to recapture Forget-Me-Not, which led to a cyclical process of Xabi being chased by the blood-thirsty group before forgetting about him and eventually seeing the video again.
In the downtime, Xabi was witness to the team’s idiosyncrasies, including perhaps inappropriate sexual relationships between some of the teammates. He also made friends with the seemingly 
sentient cleaning robots, who appeared unaffected by his power. Eventually, Doctor Nemesis created a coffee substance powerful enough to allow him to remember Xabi and explain the reason they needed his power. Xabi was annoyed that he was not simply asked to help rather than being kidnapped but agreed to put on a power inhibitor. This triggered a spy robot network controlled by X-Force’s enemy to register a new person. A drone quickly appeared and was captured by X-Force with the intention of following it back to its point of origin when Xabi’s powers reactivated. This did not happen, so psychotic X-Force member Fantomex revealed that his super-brain had always allowed him to remember Xabi, and shot him dead, causing the drone to leave. [X-Force (4th series) #10]
Luckily, the sentient cleaning robots dragged off Xabi’s body and were able to revive him through the influence of a comatose mutant named MeMe. Cable’s daughter Hope, a power-mimicking mutant, was also in a coma and had been siphoning off MeMe’s control over electronics to influence her surroundings. In this way, she was eventually able to gain the ability to remember and communicate with Forget-Me-Not, who had hatched a plan prior to the death of MeMe and of Hope returning to her coma. The revived Xabi put this plan into motion by revealing himself to X-Force and having Marrow touch Hope, in order to have her powers copied. Using the ability to grow bones now, she used bone limbs to move her comatose body and reveal some video secrets of Cable’s shady tactics.
Fantomex had since gone rogue and taken on the Volga virus to give him a massive boost in power and thus making him “perfect.” X-Force had managed to stop him by placing him in a psychic illusion of his supreme victory but Hope’s next step was freeing Fantomex and giving
him X-Force’s location. The delusional Fantomex rushed over to kill his former teammates, but Forget-Me-Not successfully placed a teleport tag on him to send him to the lab, where Hope was able to copy the powers of the Volga virus, placing her at the same level as Fantomex. However, she had the rest of X-Force (including Xabi) distract Fantomex in a fight, while she copied Doctor Nemesis’ mutant intellect so they could double team a cure for the Volga virus. Hope landed on the cure being linked to the fragile ego of Fantomex and psychically caused him to sense all of the pain and weakness of her teammates. This overwhelmed Fantomex and caused him to purge all of the impurities in his body. This results in him losing his powers and curing the virus, which Hope promptly copied. Meanwhile, the now defenseless Fantomex was beaten down by his former teammates, including the man he nearly killed: Xabi. [X-Force (4th series) #13-15]
Forget-Me-Not did not appear on anyone’s radar again until the Krakoan age was well under way. Living on the mutant island utopia, Xabi was enjoying a drink in the bar with some friends when Legion and his two walking mutants of mass destruction were forced to destroy the bar and everyone in it, due to the evil psychic presence of Onslaught. Everyone, including Xabi, were fortunately able to be quickly returned to life using the Krakoan technology of resurrection. [Way of X #4]
Perhaps Legion felt bad about this and is the reason that he recruited Xabi into his Legion of X, working as the partner of the probationary non-mutant Cain the Juggernaut. The powerful brute 
had a special device that he wore to allow him to remember Forget-Me-Not, but he annoyingly kept forgetting to wear it, making Xabi’s job all the more frustrating when Cain claimed solo credit for their deeds. This included confronting a newly-arrived mutant named Paulie, whom human authorities wanted in connection with his recently dead wife. Additionally, Xabi had developed a crush on fellow teammate, Lost though she never remembered his compliments of course. Xabi refused to condemn Paulie until they had all of the information and, during questioning and checking the records, he was able to help determine that his wife died of lung cancer, unfortunately caused as a side effect of his own smoke powers. [Legion of X #1-3]
Despite his disadvantage, Xabi did manage to get a date with Lost, which apparently went quite well. However, Lost did not remember the lovely time they had, including the lobster dinner and tequila karaoke afterwards. In order to prevent such a disappointing outcome in the future, Xabi insisted that Lost wear the same earpiece that Cain wore to remember him. As they were discussing this, they came across Cypher at the base of Nightcrawler’s home, stating that he could not gain access and that some sort of evil presence was inside. Juggernaut took that as a challenge but was rebuffed by some kind of invisible barrier. Lost claimed that there was a secret entrance for Nightcrawler’s “late night guests,” to which Xabi asked jealously if she knew that because she was one. When Juggernaut headbutted the barrier, his earpiece fell out, thus making him forget Xabi again and the secret gateway proved to be mysteriously inaccessible to Lost. Eventually, the ragtag group outside the tree were able to identify the super sentinel Nimrod as the malevolent force inside.
As Lost and Cain attempted to contact Legion for help, the forgotten Xabi successfully gained access through the teleportation gate, as the technology did not register him like the others. Inside, he was able to contact Cain on the comms and explain that Nimrod was nearly finished hacking Krakoa using a Techno-organic infection from Cypher’s friend, Warlock. Right after relaying this information, though, Nimrod located and stabbed Xabi through the chest. Poetically, Lost found Cain’s discarded earpiece and put it on, remembering the lovely date that the pair had shared. She talked to Xabi through the comms and heard how injured he was, demanding that everybody get inside the tree, finally accomplished through the combined efforts of Juggernaut empowered by the hellfire of the Spirit of Variance.
Once inside, the team was massively outgunned in their attempts to free Warlock and stop Nimrod. Just when all hope seemed lost, Forget-Me-Not yelled to Lost to remember him as he dove towards Warlock and freed him, just before being vaporized by a Sentinel. In the shake-up that occurred as Nimrod was being purged, Lost’s earpiece fell out and, unfortunately, nobody remembered the heroic sacrifice of Xabi. The tragic end of Forget-Me-Not, whose only desire was to be remembered for his good deeds, was sadly left as a skull on the floor and his friends thinking they had accomplished their mission with no casualties. [Legion of X #8-10]
Given that Xabi had returned at least once through resurrection before, it is unclear but possible that he was resurrected in the White Hot Room alongside many other fallen mutants prior to the end of the first Krakoan era. [X-Men Forever (2nd series) #2] Whether anyone was able to remember to do this for the least recognized hero remains to be confirmed. For now though, we must be the ones to remember his legacy.