Pagon was a member of the Skrull sect known as Dard'van, a believer of the Skrull prophecy that foretells the Skrull inhabitation of Earth. A male warrior, he was the lover of Queen Veranke and aided her in the Skrulls attempted invasion of the planet. Arriving on Earth, Pagon and three other Skrulls were sent to capture the assassin Elektra so that a Skrull named Siri could replace her. In the battle, Siri died but Pagon managed to defeat Elektra. Pagon, himself, took up the task of impersonating Elektra instead.
Journeying to The Hand's base of operations in the Himalayas, Pagon - now as Elektra - murdered their current leader and fought some of the ninjas proving her worthiness to lead the Hand into a new age of glory.
Pagon was created by Brian Michael Bendis and first appeared (obscured) in The New Avengers #1. he first appeared as Elektra in The New Avengers #31, written by Bendis and drawn by Leinil Francis Yu.
Pagon's death was the catalyst and lead-in for Marvel's Secret Invasion crossover event. The repercussions of Pagon's time posing as Elektra were followed up on in Daredevil, Elektra, Illuminati, The Mighty Avengers, The New Avengers and finally Secret Invasion. His origin was covered in The Mighty Avengers #16.
As with most of the Secret Invasion imposters, there are enormous continuity errors and oversights which make the whole thing hard to follow. A notable one being "Elektra" taking control of the Hand prior to The New Avengers #1, but the hand appearing in The New Avengers #11-13 under different leadership (something "Elektra" specifically even referred to in the issue where we saw him take control of them!)
Major Story Arcs
Elektra approached the super-villain Electro and paid him handsomely to help stage a mass break-out of superhuman prison known as The Raft. This was all part of a larger scheme to attract a group of heroes to a S.H.I.E.L.D. operation in the Savage Land (actually being perpetuated by Skrulls) which would cause them to suspect a conspiracy and become distrustful.
The honorary Avengers member known as Echo began making strides to battle the Japanese underworld and ran afoul of The Hand. Confronted by Elektra, Echo was killed and resurrected in the service of The Hand.
The rest of the Avengers, now a team of outlaws, journeyed to Japan to help their ally. Allying with the Silver Samurai (who was initially reluctant to help due to his vendetta with Wolverine), the outlaw Avengers were attacked by members of the Hand led by Elektra.
Luke Cage fought Elektra, Elektra trying his hardest to kill Luke Cage but unable to due to Cage's unbreakable skin. Amidst the fight, Echo awoke and following orders from the Hand stabbed Doctor Strange.
With the assistance of Jessica Jone and Wong, Doctor Strange was able to survive and free Echo from the control of The Hand. No longer under their poisonous control, Echo attacked Elektra and impaled her through the chest with a katana.
As the remaining members of the Hand escaped, Elektra fell to the floor and reverted to her true form; that of Pagon the Skrull.
Shocked by the revelation that a Skrull had infiltrated and taken control of The Hand and most of the Japanese underworld, the team of Avengers began to suspect one and another of being a Skrull in disguise. Spider-Woman proposed they take the body of Pagon to Tony Stark to see if he could help, but the rest of her team-mates scoffed at the idea believing Stark was likely a Skrull himself.
When the plane they were travelling on crashed, Spider-Woman used the opportunity to leave with Pagon's body and take them to Stark without the rest of her team.
After Stark became aware of the Skrull threat from Spider-Woman, he initially brought the body of Pagon to the attention of the Illuminati. When Black Bolt was revealed to be a Skrull and attacked them, it became apparent they couldn't trust each other anymore than the outlaw Avengers could trust each other and disbanded.
Stark, desperate to stop the Skrull invasion, brought the body before Mr. Fantastic and Yellowjacket and wished for the three of them to work out what is making the current Skrulls undetectable. Stark was called away and Yellowjacket revealed himself to be a Skrull, kidnapped Mr. Fantastic.
Powers and Abilities
Like most Skrulls, Pagon had the ability to shapeshift and underwent a process that made him undetectable as a Skrull. Pagon was an incredibly skilled combatant, a master in most forms of martial arts and able to legitimately pass himself of as Elektra.
Pagon also had access to other powers, such as Cyclops-style optic blasts, Wolverine-style claws, Thing-style bulging muscles, Mr. Fantastic-style elasticity, heat generation, size-changing and flight. Although all of these had to go unused while he was acting as Elektra for fear of alerting Earth to the Skrull presence.