Nutation
Explorer
Spiders was my least favorite episode, and a real fall from the prior episode, mainly because of the ham-fisted cartoon villain. I hope he is not a recurring character, or if he is, make him more 3-dimensional.
I doubt we'll see him again. I think the hotel owner who wants to be the American president was an unflattering caricature of the current American president who is a hotel owner.
1st - the grieving scenes - Bradley Walsh delivered a moving performance and made for the deepest and best portrayed motive for a character wanting to go off with the doctor in the history of the show (at least that I can think of off the top of my head).
Nyssa, perhaps? The Master had stolen her father's body. But, it was a great performance. Too often, the companions leave with the Doctor just because it's a lark.