This is a bit of an information dump to get the story kick started, so I made it amusing to an extent to get you through it. Don't worry, this will be the only time this happens, I just wanted to get her background out of the way so we can start to have fun with her adventuring across Seven Kingdoms with her friends. Please review!
Oh and Iris is not cruel like Lillith tends to be, but...well don't hurt those she loves...bad things happen.
Iris Potter had operated her entire life on the proven knowledge that nothing was impossible when magic was involved, in so long as you want it enough and or dispel your sense of disbelief.
She had discovered her powers at the age of seven, when she'd accidentally thrown a fireball at her big brother and had been rather understandably shocked and horrified at what she had done.
She had panicked over Dudley as he screamed and batted at the smoldering hole in his jacket and Iris's first response was to cast a healing spell on him.
Why not, after all? If she could emulate a red mage's attacks why couldn't she also emulate their support abilities? After a few moments of concentration she'd done the 'impossible' for the first time and healed the injury completely.
Hiding that damn burnt coat from their mum had been a pain in the arse though, but being adrenaline addled children they never considered trying to repair it. She idly wondered what Mrs. Figg's thoughts had been when she found said garment shoved through her back door's cat flap...musings for another day.
When she was nine, she'd cast a wandless imperius curse variant on one of her dad's coworkers to force him to stop trying to frame Vernon for embezzlement, Dudley called it her 'Obi-Wan'ing thing'. This was considered to be impossible once again when she'd later relayed it to a befuddled Professor Flitwick.
When she was ten she had immolated an ancient master vampire that had kidnapped her and her brother, afterwards she'd burnt down his mansion. She'd often called this misadventure her first random encounter, as well as boss battle.
In retrospect she really should have looted the place but Dudley, being the dutiful big brother he was, egged her on to torch it to relive one of Indiana Jones' great escapes.
He only ever told her why he'd done that this summer, when he'd found her sneaking shots of whiskey after yet another nightmare about Sirius's murder. Apparently he'd found the vampire's lolita zombie girl collection that he'd intended on adding Iris to, and Dudley hadn't wanted his sister to see it. She forgave the over protective goof of course, he gives good hugs to distraught little sisters.
When she was eleven she'd chased a terrified troll through the halls of Hogwarts cackling like a madwoman as she cast lightning bolt after lightening bolt on the thing that dared to threaten Hermione. Later that year she'd caught Professor Quirrell on fire and ganked the philosophers stone as well; to this day Iris had no idea why Dumbledore thought the power of love had vanquished the possessed man but felt no need to correct the old meddler.
When she was twelve she'd taken Lord Voldemort's first horcrux from a clearly compulsed first year student and threatened the damn thing into becoming her begrudging servant, even got a basilisk out of the deal. Oh she'd also caught Professor Lockhart on fire for being a pedophile, then Neville banished him out a window, Neville was brilliant like that.
When she'd been thirteen she killed a shite tonne of dementors, like all of them, the ones in Britain anyhow. Something else that was considered impossible beforehand but what can a young mage do? They were after her awesome prison escapee Godfather who totes promised to get her a motorbike and tattoos when she was of age, so the dementors had to go. She knew perfectly well mum and dad would never allow such a thing on their own after all.
Sirius had always been brilliant like that...she really missed the old dog...
When she was fourteen she'd slain a dragon, killed two mermen, a chimera, two blast-ended skewrts, seven Death Eaters, and a poor bunny who got in the way of one of her frostfyre curses.
Oh, she'd also caught Barty Crouch Junior on fire and Dudley had thrown him down a staircase.
When she was fifteen she tortured a woman to death, then burnt her corpse to ashes.
Umbridge shouldn't have made Luna use a blood quill.
No one touched Luna.
No. One.
When she was sixteen she'd been harangued into attending a very stupid Halloween party hosted by a...wonderful upstanding faculty member. Slughorn's nature wasn't creepy in the slightest...no sir...
Iris had been hiding by the punch bowl quietly explaining to Dudley that with or without Sirius being around she was still going to get those damn tattoos, when something many would call impossible happened.
As it was explained to her much later, a very drunk Professor Slughorn had been swinging about some ancient Egyptian scepter sent to him by some important colleague or another as he explained its significance. Suddenly, as to emphasize his loud statements he slammed the butt of the scepter into the ground causing it to begin hissing.
This was followed with the snake head top of the scepter snapping open releasing an ancient demonic scarab, which immediately made for the slightly cracked door to spread its infernal plague upon the world.
Sadly for it, Luna had set up mistletoe earlier in an effort to catch nargles, said nargles assaulted the scarab and it exploded in a flash of incompatible magics that caused one of the Professor's vampire friends to erupt in flames.
He then proceeded to run around screaming much to Iris's nostalgic amusement. She didn't have anything against the bloke really, it just reminded her of her first random encounter is all.
This led to Hermione helpfully throwing a pitcher of water on the poor vampire, seeing as how she once again forgot she was a witch who could conjure water and cast fireproofing spells. Unfortunately, the pitcher had been full of vodka and this only exacerbated the problem.
As this was all happening, Colin, who had snuck into the party, took a picture of the highly bemused Iris at the exact same moment Dobby popped into the room to help 'The Great Iris Potter', which startled Dudley into dropping his slice of custard pie.
Something in this chain of events caused Iris Potter-Dursley to jump dimensions to the world of Westeros, and for the life of her she couldn't find it in herself to be surprised when the story was later told to her.
Nothing was impossible with magic after all, just...highly improbable, and often times accomplished in a rather silly manner.
Iris's rather...interesting arson filled past had prepared her to accept quite a few things others would just disregard, her arrival to this realm not withstanding. That being said, as she was brought into the great hall of the Castle of Winterfell, sat at the table of the Warden of the North, and regaled about her ancient ancestors, she couldn't help being skeptical.
Apparently, according to Lord Eddard (who incidentally was not LARP'ing) there had been an offshoot of the family that had married off their youngest daughter to a minor Lord near what was now White Harbor. She had three sons, who as young men had all vanished as they crossed a bridge they had built over a flooded river during a great storm.
Decades later the youngest son, Ignotus, returned home speaking of a world of long lost magics, and a cloak of invisibility he had won from the Stranger himself that he had conveniently left behind with his children. Having nothing to show for his tales, Ignotus was ridiculed and shunned, thus he passed in the night, his family name dying with him.
"So you see my lady," Lord Stark continued, "as you call yourself Peverell, well it dusted off a very old fable passed down through the generations. If what you say is true, while distantly, yes, you are family."
Iris worked her lip a bit at that as the various men, and Lord Stark's wife exchanged somewhat skeptical looks before the young woman spoke up.
"Soo..." she began slowly, "How can I prove who I say I am?" One of the men snorted, she hadn't bothered to learn his name yet but she didn't like the way he scoffed whenever magic was mentioned.
"Well for starters you could show us the Cloak of the Stranger!" This earned guffawing laughs from a few of the men for some reason, Iris wasn't sure why, it hadn't been very funny.
Unfortunately, her annoyance and pride spoke before her common sense could, "Ok."
With that she pushed back her chair, stood up, pulled out the cowl of her cloak throwing it over her head. As she pulled the hem of the cloak shut it shifted from deep scarlet to watery silver, then the young woman simply vanished.
Much to her amusement most of the gathering looked gobsmacked, channeling a bit of her Dogfather she snuck up to the man who had spoken and whispered "Boo!" He screamed like a little girl as he turned around to see her pull the cowl back, bright white teeth shining from her wide grin as wine red hair pooled down her shoulders.
The still wide eyed Lord Stark simply swallowed once and nodded, "I do believe I need a drink..."
*Sigh,* why did she always get that kind of response from adults?
And now the setup is complete! On to the real story! Tallyho!
