Solomon Aran was four years old, two years younger than the six-year-old Samus, at the time of the Space Pirate attack on their human settlement. While Chief Engineer Avram Aran and Captain Thea Aran were both confirmed to be killed in the attack, Solomon was only reported missing and presumed to be dead.
Solomon is not known to have appeared in any Blood of the Chozo fan-written stories. Nintendo Power volume 84 includes an excerpt of backstory referring to him, but also prefaces the excerpt by stating that the Nintendo Power Source writer who created the frame story for Blood of the Chozo had much unused story material, implying that Solomon was one such unused concept.
In the greater Metroid series, no story material from Blood of the Chozo is considered canonical, even the original content created by Nintendo Power Source staff writers. When Samus's backstory was elaborated in the canonical Magazine Z manga, her parents were named Chief Rodney Aran and Virginia Aran, her age was three years old, and she was not shown to have any siblings. Therefore, Solomon currently has no place in the Metroid canon.
Nintendo Power volume 84Edit
"When Samus was just six years old, pirates attacked and destroyed the human settlement. Captain Thea Aran and Chief Engineer Avram Aran were both killed in the raid. Solomon Aran, Samus's four year old brother, was missing and presumed dead."