I did a double swearve once...
in my Multiverse game I had a PC get a vision of himself weilding the ruby rod and the rod of orcus...(he was a necromancer) later when he found out about the multiverse he found out some powerful casters hunted down and killed/absorbed there own alts to get more power... and the next time he had the nightmare vision he had 3 rods of Ocrus...
When the NPC he dreaded for months showed up he said "So your here to kill me?" and the other him said "Did you descend into hell or the abyss to gain evil power?" the PC swore realizing that he had turned down that power up... for the NPC to say "Then I'm here to help. I only kill and take the power of our corrupt forms" and became an ally (a super powerful one)...
the whole campagin even other PCs thought he might turn into a bad guy (the PC not his alt) and felt for sure and were even preping to fight one or both... that swearve to "No, we are the good ones" (good ish) was fun to see,