Changes

Souls are first mentioned explicitly in Supernatural in relation to the deals made by [[Crossroads Demon]]s, wherein a person agrees to give their soul to the demon upon death in exchange for some benefit when they are alive. Crowley was originally the head Crossroads Demon. The deals are traditionally sealed with a kiss, and have a set time limit at the end of which the subject of a deal, if still living, is killed.

[[John Winchester]] sold his soul to [[Azazel]] in exchange for Dean's life<ref>[[2.01 In My Time Of Dying]]</ref>, and Dean sold his soul for Sam.<ref name="three16">[[3.16 No Rest For The Wicked]]</ref> Sam attempted to sell his own soul to bring back Dean, but was the demons refusedto make a deal as they wanted to keep Dean in hell.<ref name="four09">[[4.09 I Know What You Did Last Summer]]</ref> [[Bobby]] sells his soul to Crowley to get information on Death's whereabouts in order to help stop the [[Apocalypse]]. Crowley is able to make the details of the contract he made with Bobby manifest as writing on his skin.<ref name="six04" /> The deal is undone when Bobby, with help from Sam and Dean, threatened to destroy Crowley by burning his bones.<ref name="six04">[[6.04 Weekend At Bobby's]]</ref>

[[Bobby]] sells his soul to Crowley to get information on Death's whereabouts in order to help stop the [[Apocalypse]]. Crowley is able to make the details of the contract he made with Bobby manifest as writing on his skin.<ref name="six04" /> The deal is undone when Bobby, with help from Sam and Dean, threatened to destroy Crowley by burning his bones.<ref name="six04">[[6.04 Weekend At Bobby's]]</ref> In trading for [[Aaron Birch]]'s soul, the angel [[Balthazar]] left an identifying mark on it. Castiel detected it when he 'read' Aaron's soul. <ref name="six03"/>