I thought Tiana had potential too and she did have stellar chemistry with Scott Maslen. IMO, she was his BEST pairing.
And you putting into perspective of what Diane's role is on EE is the primary reason I don't watch anymore. I just can't watch this woman be tossed aside like trash, and I felt that happened once DTC got his precious Jane back. I know many people didn't care for Ian/Denise, but I did. I thought she had great potential to become the next Beale matriarch. She has more of backbone to put Ian and his kids in place than Jane does.
Diane [and Nitrin too] get no love.
She should weep. She been there for almost ten years and she still is treated like sh-t.