Appalled at the crime in Paragon City, billionaire Justin Sinclair took up crime fighting under the guise of Manticore, a title and calling previously held by his father.
Though many would consider Justin's life a privileged one, he suffered a terrible loss as a child.
As a young boy, he bore witness to the gruesome murder of both his father and mother at the hands of a shape shifting super villain known as Protean. As a result, he grew up as an angry child and often got in trouble at school.
Michael White, a close friend of Sinclair's father, stepped in to act as a mentor to Justin.
With Michael's guidance, and his archery training with Miss Bowman (who eventually revealed the senior Sinclair's life of crime fighting and Manticore persona), Justin eventually rose to become one of Paragon City's most renowned heroes.
At first, he acted more or less as a vigilante, but after fighting alongside Positron, Sister Psyche, Synapse, and Statesman to stop Protean and the dreaded Tyranny Legion, he became a founding member of the Freedom Phalanx, in which he is still a member.
Many years passed, and eventually Manticore and Sister Psyche fell in love, and though the pair tried at first resist their feelings for each other, and later to hide them, the couple were eventually married and now fight beside each other as husband and wife.
While firmly on the side of good, Manticore's own past has given him a different perspective on the nature of evil. After watching Protean murder his parents in cold blood, Manticore became convinced that there are times when evil must be confronted in a way they can understand, with cold, calculating force.
These views often put Manticore at odds with Statesman, who is adamant that true heroes never use deadly force, no matter the situation. Their differences in beliefs leave Manticore with a mild resentment of Statesman, who he believes to be arrogant and too serious.
Manticore is a utilitarian hero who is willing to commit extreme actions if he deems them
necessary, including the use of lethal force, a practice frowned upon both in the Freedom Phalanx and within the hero community at large.
Frustrated with the limitations placed upon heroes, he secretly finances a society known as Wyvern, a group of heroes who are committed to justice at all costs. Manticore keeps his role in the activities of Wyvern well hidden from Statesman however, knowing that he would never sanction Wyvern's "eye for an eye" approach to justice.
Despite his sometimes questionable tactics and practices, Manticore is not a cold individual. He cares deeply about his colleagues and on the occasions where his actions have led to unexpected peril, he feels a deep responsibility for his teams safety.
For example, when Manticore is forced to kill Statesman to restore the superpowers of Paragon City's heroes, he quickly retrieves Statesman's body, in the hope that fellow superhero Numina will be able to revive him. When Numina is unable to return Statesman's soul to his body, Manticore immediately detonates an explosive arrow, killing himself.
He is then able to locate Statesman in the afterlife, allowing Numina to revive both heroes.
Manticore is one of the few heroes in Paragon City who operates without super powers. Though he is capable of teleportation, this effect is not a natural power, but is instead achieved through hacking into the city's Emergency Teleportation Network.
Manticore is considered a master archer, using an assortment of specialized arrows, each which cost thousands of dollars to develop and create. Though Sinclair has the means to produce large quantities of these arrows, each time one misses its mark pains Manticore greatly, as he feels that money could have been used to help those less fortunate.
Manticore feels personally responsible for fighting poverty despite his own privileged existence, or perhaps because of it, and tries to use his vast wealth to aid others, even opening a counseling and recreation center in an impoverished section of King's Row.