Elsa

Just a note, this is merely a quick summary as to how Elsa became a member of the undead. As well as what I believe it entails for her.

Starting from the beginning, Elsa was not always a vampire. She was just regular Elsa, ice powers and all until after running away from the coronation and freezing Arendelle. Whilst running through the woods she came upon a chance encounter with the one who would go to sire her. Elsa herself can't recall too much about the person. Just that he was a tall, menacing man who came from the darkness, knocked her down, then drained her until most of her blood was gone, before forcing her to drink his own.

Upon awakening, she was already near the mountain that Anna would find her at. It would not be until after the events of the movie that the actual effects of vampirism would set in for Elsa. After a series of nightmares, Elsa eventually found herself losing control and attacking Anna, almost feeding on her until regaining her sense of self.

Afterwards, Elsa and her sister would begin to take the time in order to learn more of the curse, and perhaps reverse it.

Abilities:

Aversion to the sun: As a vampire, Elsa is naturally averse to the sunlight. A romp in the afternoon would mean certain death. Though that doesn't mean that she doesn't long for its light, or warmth.

Strength: When she drinks blood, Elsa gets a slight boost in her physical abilities, which includes strength. While it's nothing really huge, it does make her stronger than normal. That being said, she still is not going to be able to lift Sven over her head anytime soon.

Speed, agility and endurance: Again, these remain normal until she drinks blood. Afterwards it increases noticeably.

Night vision: As per custom of a night-hunter, Elsa is capable of seeing far better in the dark than a normal human would be capable of. To her, it would be almost as bright as day. The drawback is that she has trouble adjusting to bright light.

Cryomancy: Elsa's ice powers do remain intake, of course, and they may be the key to her cure, and the reason why she was singled out.

Hypnotism: Thanks to her supernatural state, Elsa is capable of a form of hypnotism. While it's not something that she has mastered quite yet, she is capable of a few things. In order to initiate it, she first must be able to grab a person's attention with her eyes. After that she can become more intimidating, persuasive or friendly. Elsa may also create illusions in that person's mind; which include voices, shadows and blurred shapes.

Appearance:

Under normal circumstances Elsa's appearance had not changed at all. Though she does now sport two scars where the bite marks are. However when preparing to feast her eyes do turn a shade of red. A sign and warning to those around of her vampiric state of being.

A note about feeding:

Yes, she can make the process as painful as she wants, Elsa is biting that person, after all, and draining their blood. However she can also make it feel extremely pleasing, almost orgasmic in a sense. Whatever course of action she decides on, it still feels good for her. Blood tastes good, it is empowering and fills her with life. And being a newly created vampire, Elsa has trouble controlling how much she feeds on at times.