X-Factor Investigations is a fictional detective agency created by writer Peter David for the Marvel Comics comic book series X-Factor (volume 3). The agency first appears under the name XXX Investigations in the first issue of the Marvel Comics limited series Madrox #1 (November 2004). In the final issue, Madrox #5 (March 2005), the name is changed to X-Factor Investigations, and later to XF Investigations.
The initial staff consisted of Madrox's best friend and special enforcer, Guido Carosella (Strong Guy) and former teammate Rahne Sinclair (Wolfsbane). Following the House of M, Madrox's newfound wealth from winning a Who Wants to be a Millionaire-style gameshow allowed him to recruit several of his former colleagues of the Paris branch of the now defunct X-Corporation. New members include Siryn, a powerless Rictor, M and Layla Miller, who has inserted herself into the group to keep them from discovering the truth behind the mutant Decimation. Recently, the team has come into conflict with rival agency Singularity Investigations, after they ordered Siryn beaten and left for dead.
After meeting with Singularity CEO Damian Tryp, Madrox has asked Siryn to find out more about the Decimation from the heroes who might have been involved (by using her modulated voice to make them more suggestible). She learns from Spider-Man that the X-Men (who had denied any involvement), as well as Quicksilver were, in fact, central to the ending of the House of M and the subsequent Decimation.
Little is known about Damian Tryp apart from that he runs Singularity Investigations, which is in direct competition with Madrox's X-Factor Investigations and his encounters with Madrox's team. He is also one of the few mutants that kept their superhuman powers after the M-Day, although it has been revealed that he might not be a mutant, but a genetic throwback to an earlier time, i.e., a "changeling", a predecessor to mutants who develops powers at birth. Tryp’s mutation enables him to live for a very long time, as evidenced by him being alive in the 12th-century Wales. He also is able to move through time in a similar fashion to Quicksilver, which enables him to bring together himself at three different times.
Damian Tryp also seems to be involved in Jamie Madrox’s past. When Jamie was born, the doctor’s slap caused him to multiply into two identical babies, which was rather shocking to both his parents and the doctor. Professor Charles Xavier, a friend of the Madrox family, suggested that they move to Kansas to raise the boy in privacy with the possibility of the boy to be later taught at Professor X’s school for the gifted youngsters. However, when Madrox was still young, Tryp also makes an own offer to look after Jamie, claming that Jamie was also a "changeling" like him. Jamie's parents, however, refuse to give Jamie to Tryp, who proceeds to create a freak tornado that kills Jamie’s parents.
The all out conflict between Tryp's Singularity Investigations and X-Factor Investigations began after the youngest version of Tryp badly beat Siryn (after shooting her in the neck with a dart that prevented her from using her powers) and left her for dead. Siryn, as part of her duties for X-Factor Investigations, was investigating the murder of the woman who died in Jack Vaughn’s penthouse under suspicious circumstances. Jack Vaughn (a movie star) claimed that the woman was killed by her sister, Gloria Santiago, who was upset about the relationship (claiming that Jack was “no good” for her sister), and that all he was trying to do was wrestle the gun away from her. The sister thus hired X-Factor Investigations to help her clear her name and bring Jack to justice. Singularity Investigations was representing Jack Vaughn with Tryp, Junior (i.e., the youngest version) as the defense counsel. Siryn and X-Factor Investigations managed to incriminate Vaughn and to thwart SI’s assassination attempt on Rictor. Tryp, Junior was so infuriated by this that he ambushed Siryn and beat her almost to death, leaving her to die in an alley.
Madrox and Strong Guy give Tryp a very public warning as Tryp is jogging in the park. They tell Tryp that they know that it was him who hurt Siryn, and while they will not hurt him in broad daylight, he should watch his back. Tryp, Junior and Tryp, Senior make Madrox an offer to join their firm, and Madrox laughs in response.
Recently, Quicksilver has returned to Mutant Town following the events of Son of M, having gained the ability to restore other mutants' powers from the Terrigen Mists. X-Factor used this to confront the X-Men with their knowledge of the Decimation. As a result, X-Factor has taken a public stance in defiance of the Superhuman Registration Act and the X-Men have decided not to interfere with Quicksilver as long as he stays in Mutant Town.
It has also been exposed that Tryp and his company have been working on a new version of the legacy virus. A former Singularity employee came to X-Factor Investigations and related that Tryp was attempting to restart the Legacy Virus, the plague that killed several mutants, including, briefly, Madrox himself. Strong Guy was sent to drive the man to safety but once they were alone, Strong Guy killed him and called Tryp to report. It was later revealed that Tryp had placed a hypnotic suggestion in Strong Guy’s head to turn him into a sleeper agent. According to the oldest version of Tryp (ancient), all of Singularity Investigations' efforts to create the Legacy Virus have been to prevent a possible future in which X-Factor manages to undo the Decimation, but as a result, humanity is wiped out by the re-powered mutants in a bloody conflict. As such, X-Factor Investigations' new goal is to undo Decimation, but also to prevent the conflict Tryp predicted.
Due to one of Madrox's dupes blowing up the SI building, apparently killing Tryp, Junior and Tryp, Senior (i.e., the middle-aged version), only the ancient Tryp (the one who has been alive the longest and has seen the grim future) is still alive.
After the destruction of Singularity Investigations, the present form of Damian Tryp (the elder/ancient) reveals to Layla that her very existence had foiled his plans — she is a force of chaos like he is. Tryp also reveals that when he comes into conflict with Layla, terrible events occur as a result. Following her encounter with Tryp, Layla appears genuinely shocked for the first time: the glass of milk she is pouring overflows, spilling onto the floor.
After finding out about the foretold event, each member of the X-Factor Investigations receives a session with Doc Samson.
Madrox and Layla were sent to Forge's headquarters to send two dupes into different alternate realities. Layla jumped in with one of the dupes at the last minute, claiming she had a part to play in their mission. Unfortunately, Forge informed Madrox that there was no way to retrieve Layla and his dupes, who received instructions to kill themselves once they received the information they needed to get reabsorbed into Madrox Prime. Layla and the Madrox-dupe have since landed in Bishop's future, captured and abused in mutant interment camps.
Rictor was instructed to go undercover as a Purifer by pretending to shoot Rahne as she attacked the group's members. He has since gained information on their artillery until his cover was blown by Anole and the other New X-Men.
Rahne later joined the mutant group X-Force to hunt down Cable using their hyper-keen senses.
Siryn was called by the mutant named Peepers asking to help him out. When Siryn arrived on the scene, Peepers was eaten to the bone by Predator-X who was already on his way looking for the next mutant to kill.
Strong Guy, Siryn, and M have joined forces with the X-Men against the various groups trying to take control of the mutant baby.X-Force. Meanwhile, Rictor, while walking down a street, think he has seen Layla. After following the young girl, he finds a young prostitute who happens to appear around the same age. After some aggressive words with the young woman's pimp, he gets into a fight that leaves him wounded. After Guido joins in the fight, the men quickly disperse, and he walks with Rictor to the E.R. Elsewhere, Jamie is seen looking for a fight, and finds himself at a Purifier gathering. After shooting their leader with a tranquilizer, Jamie makes three copies of himself, and readies for a fight. Siryn reveals to a reverend that she is pregnant with Jamie's child; and later at a bar, reveals to Monet that she intends to give birth to the child.
The reasons that David chose Longshot are that he feels that Longshot's optimism and upbeat attitude would be perfect to replace Rahne and Layla respectively. He chose Armando because he is a relatively blank slate. He first appeared in a mini-series written by Ed Brubaker, Deadly Genesis, two years ago. Afterwards, Brubaker included him in his Rise and Fall of the Shi`Ar Empire storyline, which revolved around Vulcan, just like Deadly Genesis. David feels that with becoming a main character in a series, it will give him the chance to fill in the holes of Armando's history.