Scarlet Fire is a calm and collected unicorn, who steps in only when she sees fit. It's rather hard to make her upset, though bothering her friends in any way may result in the quick way of doing so. She helps her soulmate, Stretchy Straw out in every way she can, and enjoys spending time with all the Ponyville citizens. Even though loving social life, she rarely takes active action in anything, she mainly sits by on the side, watching, being a less athletic unicorn among others.
She had some sort of jealousy of Twilight Sparkle in her younger days, but those feelings got toppled over by happiness when she heard her schoolmate passing the exam and getting Princess Celestia to be her personal tutor.
Scarlet Fire used to be considered the same royalty as Prince Blueblood, originating from a family of high standards. She was attending Princess Celestia's School for Gifted Unicons, like Twilight Sparkle did, however she was but an average student, who learned quickly, and kept most things for herself. After a while, she found it tiresome and boring to meddle with the original ways of pony magic, and tried her hooves at the darker side of it, learning such spells as offensive lightning sparks and the like. She was warned by the Princess, however, to halt these studies at once. The young unicorn pony got discouraged, and left Canterlot for a much more peaceful place; Ponyville.
There, she got involved by the malevolent side of magic again, this time her spark of interest was lit by the boasting unicorn pony, Trixie. She started practicing such magic outside the town, and one night, went too far with it. She generated a ball of fire way too big, making herself unable to undo it. When she was about to release her accidental, destructive magic, a resident of Ponyville, Stretchy Straw appeared. Not minding the danger of it, the earth pony comforted Scarlet Fire back into her calm state of mind, making her able to dismiss her spell. The two quickly became romantically associated with each other, and been living in Ponyville ever since.
Scarlet Fire is skilled in the ways of combat magic, however her capability to carry out everyday spells is still basic only. Her athletic abilites go only to the extent of being a good runner, but aside this, she's not the fittest.
Scarlet Fire is in love with and engaged to Stretchy Straw.