I said up thread that I thought Brother Data would end up being the uber bad and that seems even more true now. So I actually got to thinking that maybe the whole "great evil" thing is actually a self-fulfilling prophecy--i.e. Brother Data actually becomes the great evil he's trying to prevent.
In turn, perhaps there's an artifact that can imprint false memories. Brother Data stole that too to create the false Evil Claudia memory to convince Artie that it's really a portent.