Man Horan Monis boasted he was well connected in Iran, but was "prone to grandiose claims", the inquest into last year's Sydney siege incident heard on Monday.
The inquest, conducted by the New South Wales (NSW) Coroner's Court, is examining biographical information, including Monis's background and motivations for taking more than a dozen people hostage in Sydney's Martin Place Lindt Cafe in December 2014.
Witnesses include Monis' past employers and Australian government department employees.
The lawyers assisting the commission described Monis's deteriorating mental state, including "high-functioning schizophrenia" and his unsuccessful attempts to gather a following in Australia, Xinhua news agency reported.
Counsel Sophie Callan assisting the inquiry said Monis actively sought to become involved with the Rebels Motorcycle Club some time in 2012 or 2013.
She said he had dealings with the club's Mount Druitt chapter, but they saw him as "weird".
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"Ultimately, he was rejected by the Rebels and they took his motorbike," she said.
She said Monis's attempt to join the gang provided an insight into how he was "always striving for power and influence".
"His constant goal in life appears to have been achieving significance," she said.
Callan said Monis later wrote to Attorney General George Brandis to ask if it was illegal for him to write to an Islamic State figure.
The inquest opened in January when early findings showed Monis had executed Tori Johnson, prompting police to forcefully enter the cafe.
Katrina Dawson died as a result of being struck by six bullet fragments that ricocheted from hard surfaces after police entered the cafe.
The current stage of the inquest will cover two weeks.