Thing is people don't always act as we expect. Whoever is doing it is clearly doing it to support Ryan, to be a person he can trust and feel safe with. I doubt anyone will be doing it to collude with Royce (unless whispery TA has resurfaced).
I do think it's more likely to be her fragile and probably easily manipulated sister who again will be thinking it is in Ryan's interests to support him.
Madness obviously, it was going to come out and surely will be a deal breaker for Catherine if someone trusted has gone behind her back.
Loved it, shame the old more personable police station has gone and how on earth is a tiny pharmacist able to sell a load of meds. These things will all have to be accounted for, yes he'll be forging prescriptions no doubt but surely such a high rate of diazepam dispensing would've been flagged up.