Aaron was a Mobian Echidna, the son of Rembrandt and brother of Jordan. He has the distinction of being the first Guardian of Angel Island to die unmarried and childless, and before joining the Brotherhood of Guardians.
As the last Guardian trained without the restrictions his father Rembrandt instituted after his death, Aaron was fully aware of the continued existence of his predecessors as Guardians. On his third trip to Mobius, however, he ran afoul with Dark Legion Grandmaster Menniker and a group of Overlanders with plans to launch a missile at Angel Island. Leaping atop the missile before it was launched, Aaron attempted to disarm it using skills taught to him by his grandfather, only to be attacked by Menniker. Almost immediately, his distant relative made the mistake of telling him not to press a particular switch as it would detonate the missile, Aaron defiantly did so anyway, detonating the missile and killing them both. After grieving for his son, Rembrandt came up with the Brotherhood code of secrecy while training his second son Jordan by keeping certain information, including the continued existence of previous Guardians, secret from him. This tradition continued on to Jordan's son Mathias and continued until the time of Knuckles. (KtE: #25)
A red Echidna, Aaron wore a black, open chested vest similar to Sally Acorn's, spiked guardian gloves and grey boots. Aaron also wore a band on his right foremost dreadlock.