I was reading Harry Potter Fanfic - Harry is a Phoenix animagus, trained by Fawkes, Luna is an animagus too and the mention of changing block colors reminded me of a later chapter in this fanfic involving a little girl changing the color of a magic ball of light as evidence of accidental magic. I think I originally read it on fanfiction.net. I want to say I was on a mailing list for later chapters, but I also have the vague memory that I read this in the early 2000s, so it's a slog to figure that out in the hundreds of thousands of emails. The basic gist of the story is that the Dursleys don't show up to pick Harry up at King's Cross Station (after waiting for hours with his friends, he thinks he sees Uncle Dursley, so he tells his friends to go on without him, but it turns out to be a vaguely similar stranger, with Harry realizing that his glasses were way out of prescription, leading to the misidentification). He makes his way home (walks, maybe?) only to find the house deserted and for sale. He catches the Knight Bus (I think getting splattered by mud when it arrives, so he's unrecognizable) and goes to The Leaky Cauldron to have a bed for the night, with Tom putting him up in a back room without registering him so that he can avoid notice. Harry winds up spending his summer incognito (with everyone assuming he's with the Dursleys and Tom helping him be anonymous because he sees how much this benefits Harry) and eventually meeting an American couple and their two children, and learning that the children (and eventually the mother) have magic blood in them.
Things I remember:
- There was a ghost, or just a magic mirror image, in Harry's room that would comment on his clothing choices.
- Harry went under an assumed name, I think maybe as a distant relative of Tom's
- Harry meets Hermione's parents in London at some point, where he gets contacts to replace his glasses, which also changes his eye color, leading to several people rejecting the idea that he could be Harry Potter (since he bears a striking resemblance)
- Tom finds that no magical makeup (including, I think, a vaguely Dark scar remover often used by criminals to remove distinguishing marks) will cover up Harry's scar, so Harry takes to wearing headbands.
- Harry works at a number of local Diagon Alley shops under his alias and gets known as a good hard worker
- In one of those jobs, he winds up getting something spilled on him that turns him pinkish and very rose-scented (makeup component, maybe?)
- I think there was a plot device where Harry finds a box of old childhood possessions at Arabella Figg's house, maybe when he stops in after learning that the Dursleys have fled. Aurelia had found some drawings and report cards by Harry in the rubbish bin and assumed it was a mistake, and so had set up a charm to move anything related to Harry over and had largely forgotten about it.
- Harry had a folder with the Ministry for Magic which alarmed so often (due to the borderline abuse of the Dursleys) that it had been silenced, which is later found to have been further sealed up by consequence of Harry's independence, preventing them from being able to locate him via magical means.
- I think that Dumbledore learns about the situation when they send someone over to redo the wards on the Dursley's only to have the magic backfire because the Blood ward is no longer valid. I think there was also something involving a device that puts out puffs of smoke and is tied to Harry's condition (and is seemingly less affected by the folder) but Dumbledore no longer remembers how it works. I think it might have exploded with the ward backlash.
- Someone (I was initially thinking Snape, but now I think it's a local wizard) gets sent to visit the Dursleys at their new home (in Australia?) in later chapters with the assumption that Harry is with them. There, he learns that Vernon got a promotion that required the move, and jumped at the situation, assuming that the Wizarding World would take care of Harry.
- As mentioned before, he winds up befriending an American family now living in London. The children wander into the Leaky Cauldron and Harry realizes that if their parents aren't magical, it must seem like they just disappeared. He finds the mother, indeed distraught, and after a moment of confusion, she's able to enter the pub. I think her husband was involved with the military, Air Force maybe. There are two girls, one about toddler age (maybe named Becca?), and Harry soon becomes fast friends with the family, resulting in a babysitting job where he's coached along via magic mirror by a witch from one of his former jobs, including a diaper change.
- During said babysitting job, Harry learns that one of the girls can manifest a ball of magic light (apparently something she learned to do when her parents insisted on her getting rid of her nightlight) and her younger sister can change its color (when this is eventually revealed to the parents, they note that the older sister got over the loss of the nightlight suspiciously quickly and the younger one got better at her colors suddenly).
- Harry winds up sleeping over due to the parents arriving late (I think that may have actually been the husband's arrival at the airport, him not having been there before... maybe named Steve?) and in the morning, the parents overhear him helping the girls make breakfast and sneak down to quietly observe him (the husband, in particular, being a bit leery of a young boy they don't know taking care of the girls, and a bit baffled by why his wife trusts him so much). There's a broken dish, which results in a misplaced broom whacking Harry in the nose. His understated reaction, making sure that the girls aren't distressed by his injury, wins the parents over, and shortly thereafter, the magic ball of light is manifested to calm down the younger girl, and the cat's out of the bag regarding the magical world.
- Later on, the American couple start getting hate mail from Death Eaters for being Mudbloods which just as suddenly stops because Harry considers them family, so they're under the protection of the folder's magic.
- Still later, Harry has a massive fever while visiting the family, which results in Madame Pomfrey getting called in to help treat him, which begins to unravel the whole masquerade.
- It turns out that the American mother had manifested magic as a child, but her mother had discouraged any hint of it (I think it was a religious objection), which results in an angry phone call.
I have a vague memory that the author was slowing down on later parts due to a degenerative eye condition, although I don't remember if it was theirs or their child's, eventually leading to it ending somewhat abruptly.