Jaan Devin was a Selelvian civilian who lived aboard the USS Enterprise (NCC-1701-D) in 2365, and suffered from the Selelvian disease known as The Rot. During his time aboard the Enterprise he became friends with Wesley Crusher, nicknaming him "Orange".

Jaan's friendship with Wesley was less altruistic than initially appeared, as when Jaan learned that he was dying, he—apparently unintentionally—used his Selevian power of suggestion to prompt Wesley to focus all his efforts into finding a cure for the Rot, allowing Wesley to continue his search even after he realised the truth on the grounds that he was what really 'counted' despite the fact that Wesley wasn't even allowing himself to sleep as he continued his efforts.

When a Kreel named Aneel promised Jaan a cure for "the Rot"- claiming that they had found a medical database along with various advanced weapons that the Kreel had recently salvaged-, Jaan betrayed his friends and colleagues in order to get the cure, helping the Kreel access the Enterprise armoury. However when he came to collect the cure, Aneel killed him with a phaser set to kill, reasoning that he wasn't even lying about possessing a cure as death cured everything. (TNG novel: Strike Zone)