It's to my understanding that since Tieria is one of the original Innovators (like Ribbons I suppose), he can't be controlled by Ribbons like all of Ribbons' clones can.
As far as Louise goes, those pills she takes to "help" with her cell regeneration are actually pills with nanomachines in them that allow Ribbons to "control" (re: Hypnotize) her so that she'd do his bidding. Notice when he said Gundam, she sort of stiffened, and it was like someone hypnotized her. So I'm thinking "Gundam" is her trigger word, and when Ribbons wants to control her, he basically does the same thing as he does with the Innovators. I don't think he can completely control her mind though like he did Anew. Guess we'll find out soon enough.
Also, it's good to see that the real Louise is still there. Saji was right when he said that this hardened Louise wasn't the real one. She tried to wall herself off, and Ribbons basically brainwashed her with that medicine and all, I'm thinking. Hopefully Saji will be able to get through to her again, and Setsuna won't have to kill her. I hope we don't have a repeat of Anew though. D: This series has been sad enough.