I had the idea of Sebastian possibly looking after him and Sherlock somehow finds out he's alive, but doesn't know of his condition yet. He could then think Jim is faking it at first.
He comes over when Seb is out (at the shop or whatever, it doesn't necessarily matter) and brings Jim back to Baker Street with him, or rather, kidnaps him ;) John included would be good.
I was thinking about writing a fanfic on it but I thought it would be interesting to try RPing it instead.
So... any takers? :)
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-JM ♥