Charlie and Don are lovers but don't know they are actually brothers

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Does anyone know of any stories out there were Charlie and Don are lovers but don't know that they are brothers too?  I can see this happening in a couple different ways.  They could have given Charlie up when they discovered how exceptional he was.  Don could have run away (but I can't really see him forgetting about Charlie).  Or maybe it could be a xover with the Pretender and the Centre gets a hold of Charlie.  Regardless does anyone know if there are any out there? 

Thanks a bunch,

Mina