From Halopedia, the Halo wiki
Ellie, John and their friend Katrina often built and raced in obstacle courses of their own. Occasionally their parents allowed them to go stargazing in the grasslands near Elysium City. Ellie moved off-planet before December 2517. Because her parents limited her access to Waypoint she was prevented from keeping in touch with John and did not learn of his supposed death when his flash clone died. In 2558, she was interviewed by journalist Benjamin Giraud as part of his investigation into the history of the Master Chief, where she learned, to her great surprise, that her childhood friend John became the famous Master Chief. Giraud had found Bloom through his own contacts rather than the list of interviewees ONI gave him, suggesting that her story was genuine unlike that of Deon Govender. Bloom contacted her and John's childhood friend Katrina about the revelation but the latter told her that John had died at age six, a discrepancy she subsequently brought to Giraud's attention.
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