Gail Simone came onto Deadpool during a very interesting time in DP's history. The series seemed to be going through some growing pains, attempting to draw in new readers with mini-events, like Deadpool joining Weapon X - and then later coming back from the dead, Reign of the Supermen-style. Gail Simone then come onto the book with art by UDON studios. It was nothing short of magic. The writing was incredibly deft and hilarious - giving Deadpool the kind of stories all of us fans knew he deserved. Yet before Gail had even come onto the book, plans where already in motion to change Deadpool into a new series. Simone had time to prepare some plot-points in early issues to help with this transition. Though it only lasted for 5 issues, her Deadpool storyline was one of the best the series had ever seen.
It all begins with Deadpool on a mission to kill 4 top Japanese Mob bosses. In one mistaken fall through a skylight Deadpool fired randomly as he fell - only to find he had killed all four targets. He became ridiculously famous in the mercenary world. Jobs are coming in left and right; Deadpool is even able to get himself an office, a loyal secretary named Sandi, and a homeless bum assistant. Unknown to Deadpool, the mission he's so famous for wasn't done by him, like he thought. The killing bullets, which he thought he had fired, where actually shot by an aristocratic german assassin called The Black Swan. The Black Swan lures Deadpool to germany to exact his revenge for taking the credit. Swan has a unique power - the ability to move, erase, and delete memories from a person's mind. He intends to leave Deadpool a drooling idiot and sends him back to American to suffer the indignity of loosing his mind.
Black Swan's plan doesn't go exactly like he expected, as Deadpool recovers more or less intact. Swan's agent, Jiro, follows Wade to keep tabs on him. Jiro has a personal stake in this, as his brother was one of the Mob Bosses he thinks Deadpool killed. He reports that the mind virus hasn't worked as planned, though there are signs that his mind has been effected, like him calling guns "doorknobs". Deadpool goes on with life as usual taking on new mercenary missions.
Some of these missions where truly hilarious, like trying to cut off the Rhino's horn for an aphrodisiac - and also trying to stop a Disco-hating killer from assassinating Dazzler.
The Rhino, in particular, gets shrunken down during these missions - and Deadpool keeps him around on a key chain, before eventually flushing him down the toilet.
The effect of the Black Swans' mind virus quickly becomes worse, when deadly headaches begin to incapacitate Deadpool. Wade learns from his fellow mercenary Taskmaster about the Black Swan - and then goes on a one way mission to finish things with him. Deadpool confronts Swan in his mansion in Germany. Jiro finds out that the Black Swan was the one who really killed his brother, so the Swan stabs him in the chest. Deadpool came with a bomb - intending to take Swan down with him. The whole mansion blows up in a fiery explosion, with Deadpool presumed dead.
I don't know why Marvel decided to so radically change Deadpool. He wasn't as popular as he is these days, so sales might not have been as good. For better or worse the title was changing, and luckily Gail Simone brought her A-Game to the table in creating another Merc with a mouth.
Agent X is a scarred amnesiac man. He appears out of no-where and find Sandi, Deadpool's former associate. Sandi believes that Alex is actually Wade, alive but without any memory. Taskmaster is called in, and he agrees that it is Wade, because he possesses a healing factor exactly like Deadpool's. Also like Deadpool, he has the same humorous personality. Agent X takes the name Alex Hayden. He has no memories, but he has a driving desire to be the world's greatest assassin. With Sandi's help Alex is trained by Taskmaster. Taskmaster instantly dislikes Hayden - and beats him mercilessly day after day. It's only suddenly that Alex begins being able to fight back, and out of nowhere can preform highly complex fighting maneuvers. Taskmaster is unsure who Alex really is, weather he's Deadpool or not.
After being trained, Hayden sets out to be a mercenary; for his first task he is payed with the rights to an amusement park. Alex loves this, deciding to make the place his home. Along with Sandi, Taskmaster, and Outlaw - Alex forms Agency X.
Hayden, though, gets into a deep mess against the surviving members of the Japanese Mobsters. Thinking that Hayden is Deadpool, they send a virtual army of killers to take Hayden down. It's only through the combined forces of Agent X, Taskmaster, and Outlaw that these forces are fought back against - and some cleaver thinking allows Agency X clear their names with the Japanese Mobsters.
Gail Simone was having problems with the editor and left the series by issue #7. The series would have ended right there, if not for the idea of have some fill-in writers and artists continue the adventures of Alex Hayden. These fill in where not very memorable, with the exception of a fantastic two-parter written by Evan Dorkin. Daniel Way even wrote a fill in issue here, though nothing was going to save the series from cancelation after such disappointing tales. Unless, of course, Marvel got the wacky idea to bring Gail Simone and UDON back to do a finale three issue stint. (Which they did.)
The Black Swan returns and brings a friend along with him. Appearing before Hayden and his friends, Deadpool is revealed as alive - and, more importantly, not Alex. Confused over the whole situation, the Swan explains. During the explosion that was to kill him and Deadpool, his powers of shifting memories unexpectedly expanded, allowing him to shift powers around as well. Deadpool's healing factor is seemingly shared with Black Swan and the deceased body of Jiro - and also many of their personalities and memories as well. This all gave birth to Alex Hayden, who's actually the body of Jiro, revived and mixed in with the talents and personality of Swan and Deadpool. Wishing to undo this musical chairs of personalities - Alex and the group agree to switch all the personalities back to their proper place. While doing the transfer, Black Swan finds he's able to drain both Deadpool and Hayden to make himself even more powerful. Now revived with their right memories intact, Agent X and Deadpool team up to defeat the Black Swan.
The Agent X series ended there, with Deadpool next being partnered with Cable in a new series. While Gail Simone didn't get to write as much Deadpool material as could have been - she still delivered on an incredible series. Deadpool is currently now much more popular, so I don't think we'll ever see his book so re-arrange like this again. Agent X still makes some appearances in later Deadpool issues, though regrettably he is made morbidly obese. He's trying to loose weight, having lost 3 pounds thanks to Jenny Craig. Not the most dignified of ends for a character Simone made so cool.