My Harry's in the Highlands

Harry and Felicia are climbing up a huge tree so Harry can develop his survival skills, although he's moaning about it all the way through. As they reach the top they are unaware that a rather large bat is heading towards them. Felicia says it's time to head back down but Harry say's that's easy and uses his magic to start floating downward, to the criticism of Felicia.
 

But then disaster strikes when the giant bat appears on the scene and grabs Harry, hits Felicia down to the ground and then knocks out Harry with a orange beam. Cue commercial break!
 

The bat lands near a rock face and it then changes into it's true form of Morrigan, who takes Harry inside a secret cave. The next scene is one that I don't get. A farmer goes and puts a meal out on the middle of a tree stump which is surrounded by sheep. Talbain then appears, and instead of attacking the sheep he takes the meal. There are then several pointless shots of Talbain running off before he starts to eat. Then we have a rather strange flashback.
 

One day there was a food shop that a young, human Talbain liked looking in. But then one day everything blew up. End of flashback. I don't get it either.
 

And then as the flashback ends Felicia suddenly shows up demanding Talbain's help to find Morrigan. Back at the cave Morrigan finds Harry awake and reveals her plan: she wants him to become her pupil so she can gain much more power and then casts a spell on him to bring him under her control. Meanwhile Felicia and Talbain start to track Morrigan's whereabouts.
 

Morrigan tells Harry that he is under her control and then makes him say a few magic words, then she blasts the lake they are near which reveals the ancient ruins of a city Morrigan calls "Warlock Haven"...
 

...but before they can enter Felicia and Talbain show up and start to fight them. Felicia can't believe that Harry is attacking her whilst Talbain and Morrigan fight each other. Morrigan eventually manages to push Talbain back and then she and Harry jump through the portal which then vanishes before Felicia and Talbain can follow after them.
 

Later on Felicia is moping about how Harry has joined the evil Darkstalkers but notices that Talbain has vanished. That's because he's gone back to the town to get some diving equipment. And to get it he breaks a door and simply steals it, how naughty.
 

Talbain takes the diving equipment back to Felicia and gives it to her (apparently he doesn't need any) and the two dive down into the lake and eventually break through into Warlock Haven, where Morrigan and Harry are busy resurrecting "Scotland's ancient warriors" as Morrigan calls them.
 

The warriors climb out of the ground revealing themselves to be skeletons with armour and weapons, although Morrigan says that they are immortal. Talbain quietly beats up a few though and takes their armour, which he and Felicia then wear. Meanwhile Morrigan says that with this army she'll crush Pyron and make Demitri her servant. Felicia and Talbain walk up but Harry instantly recognises Felicia and alerts the skeleton army.
 

The supposedly immortal skeletons attack but are easily beaten by Felicia and Talbain. Felicia then picks up some blue goop and throws it at Morrigan and Harry, which for some reason frees Harry from Morrigan's spell when it hits him. Morrigan then warns that it was Harry's power that was preventing Warlock Haven from being flooded again so...

...water rushes into the place and everyone is blasted back up to the surface. Morrigan grabs Harry and takes him to the shore before Felicia and Talbain resurface, and tries to put Harry under her spell for the second time.

Harry manages to resist though and now Morrigan's plan to make him her pupil has failed. Morrigan says that Harry has destroyed her plans one to many times now and flies off with him. Meanwhile Felicia and Talbain get out of the lake and Felicia says she knows where Morrigan and Harry have gone as she can smell them, so they head after them. Morrigan takes Harry to the place where she was sealed in a rock two hundred years a go by a couple of white witches before she was freed thanks to Pyron/Demitri. Harry asks if she's going to seal him in a rock...

...but she says she will throw him off instead as the other way will take too much time. Before she can though Felicia tackles her, only for Morrigan to drop Harry and have him fall off the cliff anyway, but he manages to grab a branch on the way down. Morrigan and Felicia fight but Morrigan hits Felicia with a projectile which knocks her out.

Harry climbs up the cliff only to find Morrigan waiting at the top ready to blast him off, but then Talbain appears and pulls Harry up before Morrigan can do anything. Harry goes off to tend to Felicia whilst Talbain and Morrigan fight each other. Morrigan appears to have the upper hand when she uses her power to cast several pillars around Talbain...

...but Talbain simply howls really loudly to smash them all. Morrigan decides that it is time to leave and takes off, but Talbain leaps after her and grabs onto her, and they both fall into the lake below. Felicia really cares.

Felicia and Harry go and take a look round to find Talbain but at first they see Morrigan being beamed up towards Pyron's spaceship. They then find Talbain's body but he has reverted to his human form.

He wakes up but then the full moon appears from behind the clouds and Talbain changes back to his wolf form. Harry says sorry for the trouble he caused but Felicia says that it wasn't his fault, it was Morrigan's, whilst Talbain basically implies that the next time he and Morrigan meet, he'll destroy her.

What's the deal with human Talbain? Is it the moon that controls his transformation like the end of the episode suggests? Because if so why is he not in his human form during the scenes set during the day in this episode?

And what on Earth is that flashback all about? It's never explained.

This is one of two episodes that Demitri doesn't appear in (although he is mentioned by name a few times). The other episode was the previous one, Aliens Keep Out.