I'm simply going to explain why Dane would never be able to possess Nathan.
Nathan is legit a cryptid himself, he's like that one strange relative that always looks terrifying and out of place in family photos. The one the family is always hesitant to talk about.
He also probably lives in their walls too.
But as soon as someone f**ks with his family, he crawls out of the darkness just to whoop the ass of whoever thought it was okay to do so.
Legit Nathan is unpredictable, he barely talks and when he does he says something outlandish, you can't tell what he's thinking or planning to do most of the time.
So it would be hard for Dane to even try to play his tricks on Nathan since Nate would either ignore them or simply not care. It wouldn't do any good to get in his head either since Nathan's brain is essentially in limbo, like he's there but he's not. And there’d be nothing for him there to use as a way to manipulate Nathan so he’d essentially just be wasting his time.
Dane would have no use of just existing in a dark void.
That's legit like trying to possess Slender Man it's literally impossible.
It would just be like another Freddy Vs. Jason situation.
He could try to use Nathan’s status as the odd one out of his family against him but it wouldn’t do no good, even though he knows Murdoch and the rest of his siblings fear him as long as they’re safe he doesn’t care what they think of him, he knows deep down that they love him and that’s all that matters.