Freya

Freya was a druid girl who fell in love with Merlin.

Early Life
One day, a sorcerer attacked Freya and she killed him in self defense. When the sorcerer's mother found out, she cursed Freya to become a bastet, a magical monster that resembled a large panther with bat-like wings, on the stroke of midnight with an insatiable desire to kill that she would be unable to control. This eventually got her cast out of Druid society, despite the Druid's belief to never turn away someone in need.

Death
Under unspecified circumstances, Freya was captured by the bounty hunter Halig and taken to Camelot, only to be freed by Merlin. Hiding Freya in the underground catacombs, Merlin brought her food and told her about his magic, the two being drawn together due to Merlin's relief at having someone who understood him and Freya's gratitude at meeting someone who did not consider her a monster. This bond eventually blossomed into love. Unfortunately, Freya's curse resulted in the deaths of at least four people when she transformed during her two nights in Camelot, prompting an increased hunt for her.

Although Merlin had planned to leave Camelot with her, Freya attempted to escape on her own, not wanting Merlin to abandon his life for her, only to be cornered by Halig and Arthur's knights just before her transformation. Although she killed Halig, Arthur was able to fatally wound her beast form, the creature only escaping after Merlin caused a distraction by causing a gargoyle statue to fall over, retreating down to the catacombs where she met Merlin again. Although beast-Freya appeared calmer around Merlin, not even attempting to attack him, the wound Freya had sustained proved to be mortal, staying alive only long enough for Merlin to take her to the nearby lake. As she died, she thanked Merlin for making her feel loved, promising to repay him one day.

When Merlin met the Fisher King, the king gave him a gift, water from the Lake of Avalon, the same lake Freya was laid to rest in. The Fisher King spoke prophetically that, "Albion's time of need is near and in that dark hour you must be strong for you alone can save her. Your powers are great, but you will need help and that is what I am giving you," and handed him the bottle of water. (The Eye of the Phoenix)

Return from the dead
After Morgana and Morgause took over Camelot, Merlin attempted to use his magic on the water to no avail. When Gwaine got up to "answer the call of nature", Merlin accidentally dropped the bottle, breaking the glass. Merlin was horrified when the bottle broke and watched helplessly as the water spilled and flowed away thinking that he had just lost Albion's last hope. He was quickly shown that smashing the glass had actually allowed him to use the water instead of wasting it. It glowed magically and formed a puddle in a rock crevice. Freya's image materialized as the water settled, smiling at Merlin. Merlin was shocked, confused but nevertheless delighted at the sight of his beloved Freya.

Freya tenderly told him that she missed him, but time was short and she couldn't explain how she had become the Lady of the lake. She informed him that only Excalibur could destroy Morgause's immortal army and told him that she would hand him the sword to repay him for everything that he had done for her. When Merlin travelled to the Lake of Avalon, Freya gave him the sword though only her arm emerged from the lake. (The Coming of Arthur part 2)

Because it has been stated that Freya will become closer to Merlin and they had very little time to talk when Merlin contacted her, it is possible that Freya will return in series 4.

Personality
Before meeting Merlin, Freya was traumatised by her curse, both physically and mentally, and hated herself for being a Bastet. She even called herself a monster at one point but did not know how to tell Merlin about her curse. She desperately wanted to be an ordinary person with an ordinary life. Freya said that before she met Merlin she'd always had to look over her shoulder to make sure she was not about to be ambushed. This trait most likely originated from when she was attacked by a sorceress' son.

Freya was a nervous and shy girl and when she first met Merlin she was worried that he was going to try and hurt her even though he'd freed her from Halig's cage. However, despite her fragile exterior, Freya was stronger than she appeared and was surprisingly independant as she was able to defend herself from the man who attacked her and survive on her own after her family died, though it is unknown how much time had passed since then. She quickly grew to trust Merlin greatly and fell in love with him. Merlin fell in love with her in return.

Though she hadn't been close to anyone since she was cursed, Freya was very loyal to people she cared about and even returned from the dead in order to fulfil a promise she made to Merlin. She was also selfless and did not want Merlin to give up his life in Camelot for her sake, believing that he could have a better life in Camelot. Therefore she tried to escape on her own but was cornered by Arthur, Halig and Arthur's knights before transforming into the Bastet. Freya was grateful to Merlin for loving her and promised to repay him someday even though she was dying when she made the promise.

As the Bastet, Freya was a bloodthirsty killer killing at least five people during her time in Camelot including Halig. Though Freya was usually unable to stop herself from killing in her beast form, she did not attack Merlin when he stroked her, proving that the strength of their bond was even stronger than the strength of her curse.

Abilities
Freya was magical but she thought her magic was a curse. It is assumed that she used magic to kill the man that attacked her, since she stated that she didn't mean to kill him and she was likely unable to control her powers. Before her death Freya had the ability to transform into a Bastet every night but was unable to control this ability unless she was around Merlin.

Freya also somehow returned from the dead as the Lady of the Lake though how she managed this is unknown. However her magical abilities probably had something to do with it, along with the magical properties of the Lake of Avalon.

Appearances
Series 2:

The Lady of the Lake (first appearance)

Series 3:

The Eye of the Phoenix (mentioned indirectly)

The Coming of Arthur: Part Two

In the legend
Freya's name is never mentioned in the Merlin legend but she is based on The Lady of the Lake. Like Freya the Lady of the Lake is Merlin's lover.

Norse Mythology
The name Fraya (sometimes spells as Freyja) is the Norse Goddess of of Love, Fertility and Sexual Desire.

The other half of the heroic warriors, who belonged to Odin (King of the Asgard, Ruler of the Æsir, God of Death and Knowledge), would be gathered up by the Valkyries and taken to Valhalla where they were able to live in comfort and honor.

Fraya was also called upon to comfort those who were dying, to ease their transition into Valhalla (the "Otherworld"), serving as a guide and companion on the journey to Valhalla for many Viking heroes who had died nobly.

When Freya and the Valkyries rode forth on their missions, their armor caused the eerily beautiful flickering light that we know as the Aurora Borealis, or Northern Lights.

Fraya is the wife of Od, the daughter of Njord, twin sister of Freyr and mother of Hnoss and Gersemi.

Many songs today praise her.