Before Sean was killed by Cromm Cruich, he was a ghost. He actually died in the 1950's when a gas pipe in his house leaked. However, for whatever reason, he didn't pass on from our plane of existance, and simply continued to perform his routines until Mirth broke Kevin out of jail. At that point, events confronted Sean with what he was, and, recognizing Kevin, he become the fourth member of the group (which consisted of Kevin, Mirth, Edsel and Sean). If not for Kevin and Mirth, Sean would eventually have faded away over time.
Later, when Mirth went into hiding, and while Kevin still denied his heritage, Sean became the leader and planner for the group. He died his final death protecting Kevin from the Worm of the Mists (dragon), Cromm Cruich.
Sean had all the classical powers of a ghost - incorporealness, fear projection, the ability to enter the "Faerie Lands", life support and a high degree of resistance to injury. Some forms of magical attacks affected him (e.g. Cromm Cruich), while others didn't (e.g. elf-bolts). So to make his Desolidifcation work against magic, it was bought at the 60-point level and his weakness was mental attacks. Sean also had limited precognitive abilities (bought as Danger Sense), which were fickle and had the side effect of intense abdominal pain. While fighting Cruich, Sean broke a light bulb, stuck his finger in the socket, and channeled enough electricity to cause Cruich pain. (At the time, Cruich was shape-shifted into human form.) Because he was a ghost, his memory was deteriorating rapidly. He had no memory of his childhood, his youth, or really anything beyond his immediate duties; sometimes he couldn't remember details of the previous five minutes.
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I was a ghost!
Also:
Sean was killed by his own bomb in 1974
I blew myself up!
Edited by Sean, 11 January 2006 - 04:20 PM.