I watch Smallville, so I get the Lana reference.
She had about 40 different personalities in 8 seasons.
From waitress to witch, to a Luthor, to a super woman? Makes my head hurt.
With Brenner, it comes down to sloppy writing and not enough time to make the character legit. Brenner got brought in as a sterotypical villain who the audience was supposed to hate. Now he's Mr "I wanna go to Venice, treat you like a queen, be your one and only, and make you mine after 5 seconds of dating". The two don't really fit together, so he is never going to be well-received by most of the audience.