Smallville series finale?

for the lex part, it was gonna be a clone a perfect clone with tess's heart. but since tess shot lionel, the darkside came to him and gave him a deal and lionel asked for him to save lex and he can take him instead. so my take is that the darkside brought back the real lex. and yes what tess put on him was a chemical to make him forget everything. it was tess's way of helping clark keep his secret from lex....so the lex we see at the end, has no idea who clark kent really is..hence, their great enemy sl for the future..