Emmerdale's Dr Crowley theory

I'm not sure if this contains any spoilers to be honest but I marked it in case. I just find Dr Crowley such a weird addition to the show and Joe's storyline

Something is telling me that either he isn't really a doctor, or he has ties to the Tates. Why would he help Joe and go to so much length and secrecy to do so? How comes only Joe has seen him, and no one's seen him sneaking into home farm?

The relationship between Joe and Crowley just seems a bit closer than doctor and patient? He seems to be going all out to help Joe and whatever their plan is?

I wonder if the reason he's not been with other characters onscreen yet is because someone might recognise him or know who he is? I saw someone suggest he wasn't real and was in Joe's head so that's also a possibility? But who do people think he's linked to if anyone, and what's his game?