Soulbonding was coined by Amanda Flowers in 1998~ on the Just For Writers (aka JFW) mailing list (though since it was a mailing list, the exact date is hard to pinpoint). Originally it was spelled as SoulBonding; based off the title of the rpg SoulBlazer. The term got spread to more people and in 2002 the first Live journal community dedicated to soulbonding was created. When the community came in contact with the multiplicity community on LJ, the two began intermixing, which caused infighting in both communities about the nature of soulbonding and plurality. As time went on, information about soulbonding became harder to find as websites were taken down, and (from what we have seen, so take this with a grain of salt) the community became absorbed into the plural and fictionkin communities.
A summary of soulbonding history
Further reading