Peri: A Theory
I meant to discuss this earlier. Finishing "Planet of Fire" left me with a theory about Peri. I think the Doctor took her along because he was really really depressed at the time.
The Doctor's interactions with Peri go about like this, over the course of the episode:
* First Howard, then Peri, emerge from ...wherever Turlough's been keeping them.
The Doctor: "WTF are all these people doing in my TARDIS???"
* They turn up on Sarn, and plot start's happening.
The Doctor: "Well, we're doing a thing here for the moment - stay in the TARDIS and I'll be back later."
* Peri has her own private subplot with the Master and Kamelion, which ends up with her inside the volcano control chamber.
The Doctor: "Oh, this is where you got to. Well, okay, hold down this switch for me."
* The Doctor kills Kamelion, and then the Master (during which time Peri is waiting in the TARDIS. He is visibly upset by this (that is, he stares blankly into space with an expression of Dull Surprise) - if anything more on account of the Master than on account of Kamelion.
* The Doctor goes back into the TARDIS and continues to stare blankly into space, until Peri reminds him that they're inside a volcano that's about to explode. It's this second bit of staring that's significant - he's clearly not okay with what's just happened.
* Turlough decides to go back to Trion. He and the Doctor are both pretty emotional about this, in a "we're being manly and not at all emotional" sort of way.
* The Doctor goes back into the TARDIS, where Peri is still hanging out, and starts fiddling with things.
The Doctor: [distractedly] "Okay, let's get you back to earth then."
...and then Peri fumblingly ask to go with him. And he kind of stares at her. (In kind of the same way he was just sort of staring after the Master went all crispy). And what's his response? Not "glad to have you", or "welcome aboard" or "it'll be dangerous, are you sure?" No, what he says is "sure, why not."
He's just lost his Best Enemy, his Robot Buddy, and his Red-Headed Stepchild. He probably is still not recovered from Tegan's abrupt departure (he certainly wasn't at the beginning of the episode). He's got other things on his mind, and this Peri person keeps turning up somewhat unexpectedly. Oh, and now she wants to come along. Sure, why not. It's not as if things can really get any worse.
...yeah.
I think overall the Doctor's reaction to Peri is one of dumbfoundedness. He certainly has no idea who she is and what she's doing her (or what to do with her) in this episode. She emerges from the TARDIS and he's like "Where the heck did you come from? Never mind, plot happening now - I'll deal with you later." The pleasant bits at the beginning of Caves of Androzani have a few moments of him looking at her and going "WTF?" (Actually, I believe the line is "Sarcasm does not become you" but what it means is "WTF?"). And then they both spend a lot of time dying, and then he's a new person, and most of his interaction with her is "WTF do I do with you now?" That's the tragedy - he does try . He spends a lot of time in the Sixth Doctor era trying to impress her or be nice to her, but he has no idea how to do it. Especially after the strangulation incident.
But even from the beginning, he has no idea what to do with Peri. So sure. Why not?
The Doctor's interactions with Peri go about like this, over the course of the episode:
* First Howard, then Peri, emerge from ...wherever Turlough's been keeping them.
The Doctor: "WTF are all these people doing in my TARDIS???"
* They turn up on Sarn, and plot start's happening.
The Doctor: "Well, we're doing a thing here for the moment - stay in the TARDIS and I'll be back later."
* Peri has her own private subplot with the Master and Kamelion, which ends up with her inside the volcano control chamber.
The Doctor: "Oh, this is where you got to. Well, okay, hold down this switch for me."
* The Doctor kills Kamelion, and then the Master (during which time Peri is waiting in the TARDIS. He is visibly upset by this (that is, he stares blankly into space with an expression of Dull Surprise) - if anything more on account of the Master than on account of Kamelion.
* The Doctor goes back into the TARDIS and continues to stare blankly into space, until Peri reminds him that they're inside a volcano that's about to explode. It's this second bit of staring that's significant - he's clearly not okay with what's just happened.
* Turlough decides to go back to Trion. He and the Doctor are both pretty emotional about this, in a "we're being manly and not at all emotional" sort of way.
* The Doctor goes back into the TARDIS, where Peri is still hanging out, and starts fiddling with things.
The Doctor: [distractedly] "Okay, let's get you back to earth then."
...and then Peri fumblingly ask to go with him. And he kind of stares at her. (In kind of the same way he was just sort of staring after the Master went all crispy). And what's his response? Not "glad to have you", or "welcome aboard" or "it'll be dangerous, are you sure?" No, what he says is "sure, why not."
He's just lost his Best Enemy, his Robot Buddy, and his Red-Headed Stepchild. He probably is still not recovered from Tegan's abrupt departure (he certainly wasn't at the beginning of the episode). He's got other things on his mind, and this Peri person keeps turning up somewhat unexpectedly. Oh, and now she wants to come along. Sure, why not. It's not as if things can really get any worse.
...yeah.
I think overall the Doctor's reaction to Peri is one of dumbfoundedness. He certainly has no idea who she is and what she's doing her (or what to do with her) in this episode. She emerges from the TARDIS and he's like "Where the heck did you come from? Never mind, plot happening now - I'll deal with you later." The pleasant bits at the beginning of Caves of Androzani have a few moments of him looking at her and going "WTF?" (Actually, I believe the line is "Sarcasm does not become you" but what it means is "WTF?"). And then they both spend a lot of time dying, and then he's a new person, and most of his interaction with her is "WTF do I do with you now?" That's the tragedy - he does try . He spends a lot of time in the Sixth Doctor era trying to impress her or be nice to her, but he has no idea how to do it. Especially after the strangulation incident.
But even from the beginning, he has no idea what to do with Peri. So sure. Why not?