On the night of Halloween in 1981 James and Lily Potter died and their son, Harry, was taken away to live with his aunt and uncle. Had Hagrid, the man who took the toddler, known that Athena, the Potter's cat, was under the couch he probably would have grabbed the little fellow. But Rubeus Hagrid did not know the cat was there nor did any of the numerous visitors to the wrecked house, so Athena was not claimed by any magical officer. It wasn't until she stalked out on to the streets of Godric's Hallow that she had any human contact, but that was not what she'd been hoping for. A thick net, wired cage, and scraps of dry food were all she saw for a very long while. She saw words too, words that read Animal Control but of course Athena didn't know that. Athena was a cat, and just as Vermon Dursley mused only days before, cats can't read.
Shelters are no place for a cat, especially those used to the abundant attention of a toddler. If cats could be diagnosed with depression she most certainly would have been, but no one cares for a cat's mental well being If they're not hurting anybody let them be. So little Athena was left alone scarcely seeing humans except for when she received her meals at 9 and 5. It wasn't the worse life; Harry was already being tormented far more by his new family, but it definitely wasn't a good one.
Arabella Figg wasn't very happy either, because she'd recently moved to Little Winging to keep an eye on Harry Potter and found the neighbors most frustrating. Her husband had died in the war, and living alone as a squib was never easy. To be half in and half out of the magical world was a terrible fate, but one few shared with Mrs. Figg. Athena shared it, having lived the first year of her life around magic, but up until that point neither being had found the other who could understand their predicament.
Mrs. Figg had never been rich and upon her husband's death the widow needed a new way to earn a living. She'd had kneazles as a child and figured she could make money by crossbreeding them with normal cat and selling to muggles. The thing was, however, that she needed cats to breed them with. Most shelters spayed or neutered their animals upon arrival, but Athena just so happened to be in one of the few shelters without the funding to undergo such procedures. It was because of this that Mrs. Figgs found herself at the same shelter where Athena had been residing since her owners sudden death. (For though the magical community celebrated Halloween of 1981, it was the worst day of that young cat's life.)
On each cat's cage was his or her gender and the reason each animal had been brought in. When Mrs. Figg noted that Athena had been found wandering Godric's Hallow, she wondered if maybe this cat had, at one point, belonged to a witch or wizard. Noting both the cat's beauty and the possibility she'd not be as startled by the magical kneazels she'd live with, Mrs. Figgs adopted Athena, named her Lily after the fallen friend and the petal design of her pelt, and brought the cat to the home she'd live in for many long years.
By the time he was three years old, the Dursley's had already begun dropping Harry Potter on his neighbors doorstep and since Mrs. Figg was willing to take in the orphaned wizard, he spent much time at her house. Athena had been shocked when she recognized the growing boy, and though he never recalled her the last two Potters spent much of their life growing up together.