The Birth: Sprite joined the X-Men when, like Jubilee, she was still a minor. Her story unfolded in the Uncanny X-Men #129 (Jan,1980). She is the brainchild of writer Chris Claremont at the onset of the Dark Phoenix Saga in Marvel comics.
When a 13 year-old Katherine Pryde returned from her dance class to her home in Deerfield, a suburb of Chicago, her parents were chatting with a Ms. Frost (Emma Frost, the Hellfire Club's White Queen), who claimed to represent a school in Massachusetts. At that time, both, the Hellfire Club and the X-Men knew about Kitty Pryde's mutant powers. Each group wanted to acquire the girl. Suffering from a bad headache, Kitty hit the sack. But somehow, she phased right through the bed and her room and landed directly on the floor of the living room. Her parents who had just entered the room were a bit surprised to find their daughter on the floor, but she made an excuse of having tripped and fallen.
Later that day, Professor Xavier arrived at the Pryde's house, accompanied by Colossus, Wolverine, and Storm. The Professor discussed his school for gifted youngsters with Kitty's parents while the X-Men took her to the Malt Shoppe. Her parents already knew that their daughter was a mutant and wanted the best options open for her. That's when the Hellfire Club attacked the house. Kitty instinctively phased through a brick wall, thereby evading capture. Emma Frost arrived on the scene and the group captured the X-Men. Unnoticed to them, Kitty Pryde sneaked aboard their hovercraft.
Later, while the X-Men were held prisoner, Kitty dialed Professor X's car phone number and was answered by Nightcrawler. While the Hellfire Club troops attacked Nightcrawler, the other troops were after Kitty Pryde. Fortunately, the remaining X-Men defend themselves and reach Kitty in time. After she narates her story to them, they plan a rescue mission disguised as Hellfire troops. Of course, they manage to save the captured X-Men.
After Kitty returned to her parents, her father took the decision to send her to Xavier's school for gifted youngsters. Kitty Pryde officially joined the X-Men in Uncanny X-Men #138 (Oct, 1980).

The Alter Ego: Sprite's real name is Katherine "Kitty" Leeann Pryde. A mutant from birth, she got involved with the "superhero" bit when she was still quite young - at age 13. Kitty could still be immature at times and quite often did things without thinking.
Kitty has shown a natural talent and is considered a genius in many areas: among them being computers and physics. As a matter of fact, Kitty at first thought Prof. Charles Xavier was recruiting her for his school due to her knack for Physics. Kitty was often seen working with computers, and wrote many programs with Douglas Ramsey, former New Mutant's member Cypher, who died in the line of duty defending her current team member Rahne Sinclair.
Kitty Pryde, as a person, seems to bond very deeply to those she feels close to. Empathy comes natural to her as she is a very caring person by nature. In the past she felt when her best friend Magik was in trouble. She has also made a best friend out of the alien dragon Lockheed.
Initially, because of his appearance, Sprite was treating Nightcrawler unjustly, but later when her eyes were opened by another mutant called Caliban, she realized she had been wrong and apologized to him. She holds thick bonds with Storm, Wolverine and Collossus.
As for her romantic interludes, Kitty has always had a soft corner for Collossus.

The Legend: After joining the X-Men, Kitty Pryde needed a psuedo name for herself. She rejected Xavier's choice of Ariel but liked the name that Storm gave her - Sprite. Sprite's first challenge was when the timeline went haywire and her future self came into the present to save Senator Kelly. Her next case was the fight with an N'Garai Demon who had entered the X- Mansion. Later on, she modified her uniform and felt it was much better than her old one. But Professor Xavier informed her that an individual uniform had to be earned. In an effort to prove herself, she stowed away in the Blackbird and went up against Magneto.
Some time after this incident, Kitty's parents decided to withdraw her from Xavier's school and put her in Ms. Frost's School. On her very first day in her shcool Sprite realized that it Ms. Frost was reallt Emma Frost and with the help of Storm, she fled the school. Back again with the X-Men, Sprite went up with more villain. One of them was a Shi'ar Dreadnaught who had kidnapped Empress Lilandra. After a scuffle in which Colossus was believed to be dead, Sprite vowed revenge on the Shi'ar.
She discovered the treachery of the Shi'ar Admiral Samedar, and prevents a guard squad from killing Nightcrawler. Kitty then changes costumes yet again to masquerade as Phoenix, scaring the Shi'ar witless. Kitty and Nightcrawler then confronted Oracle to inform her of the admiral's intent. Oracle mobilised the Shi'ar Imperial Guard against the admiral. During the fight, Kitty phased her way to the primary computers, disabling them. Of course, after that victory, she found out that Colossus was alive and well.
Another contribution she made to the team was an idea to wipe out all records of mutants from Federal computers in order to protect the X-Men from Government action against mutants.
She has also confronted the likes of Dracula when he tried to change Storm into a vampire.
Later on, as her skills developed she joined the group Excalibur when she and Nightcrawler thought that the rest of the X-Men were killed in battle. She also changed her name to Shadowcat, a name which she still goes by.
As for her powers, she is a genetically superior being due to a quirk in her genetics known as the "X-factor". Kitty has the mutant ability to make herself intangible by "phasing" her molecules through another object. This ability works on things she is touching as well. Unfourtunately it also has a horrible tendency to mess up any and all electronic systems she comes in contact with.