The one problem seen with Tegan and Turlough in Cobwebs, was that they were slightly written uncharacteristically. Tegan did argue with the Doctor at times onscreen, but the way she came across at times in the audio, especially when Nyssa reunites with them, is completely not like her at all. She came across jealous, dripping sarcasm at the Doctor and even came across slightly hostile towards Nyssa, which is really unlike her, as Nyssa was always her best friend, or even like a sister to her. But at least she had Turlough siding with her at this point. So with that said, we now can establish Cobwebs takes place after Enlightenment and in between the King's Demons. As in the beginning Tegan argues with the Doctor about how Turlough had been trying to kill them both, but especially the Doctor. Of course, the Doctor keeps assuring her it was due to the influence of the Black Guardian
One thing about Janet Fielding's return, is that even though she had been gone from the world of Doctor Who for so long, when she finally decided to come back, she easily slipped back into the role of Tegan Jovanka. The listener can't even tell that there has been such a time gap since Janet has played her character.
Turlough is much more outgoing in this audio. He is not under the influence of the Black Guardian any longer, and he is willing to work with his friends more so then before. Mark Strickson is always spot on as Turlough, and like Janet, he seems to jump right back into his character comfortably.
The Fifth Doctor is the same as usual; always ready for exploration and adventure, and in Cobwebs, it's no different. But it's the ending of Cobwebs, which won't be revealed, that is very much like the Fifth Doctor. Because he's always one to get involved, even though he really shouldn't interfere, and he knows this, but he does it anyway. That's how the Fifth Doctor is. As soon as they land, the Doctor is eager to explore.