There's an autistic boy at my preschool. He's 4 now, almost 5. Didn't start speaking until he was nearly 3, but then quickly learned to count up into the thousands in 5 different languages. He's Czech but learns English so fast it never stops amazing me. I don't have to teach him anything, just talk to him and he understands and remembers every word. I'm in love with him and if he were about 20 years older I'd marry him immediately.
His main obsession is numbers, but he has smaller obsessions that change over time. Once he learned the entire Czech name day calendar (he still remembers whose name day it is every day). He knows how old I am and how tall I am in cm. For a while he took every toy with a sliding part, declared it an "elevator" and described the wonderful things on each floor from -100 to 100, including parking lots, peoples' houses, colors, animals, and more. He once spent several weeks walking around with a rubber duckie repeating "kač kač kač" (the Czech word for "quack") and insisting that the duck answer all questions posed to him. Yesterday he was drawing Roman numerals all over the big outdoor chalkboard, pointing at them and reading them: "X I V is FOURTEEN!"
His current obsession is my favorite yet. You know the intro to Pixar films, where the lamp jumps on the letter I until it squishes it?
He's been taking sets of 5 objects - any object will do - and lining them up as though they were letters. He points to it and says "this is Pixar." (Oh, he's been able to read and write for nearly a year and knows the alphabet in both Czech and English.) Then he takes a spare item, declares it a "lamp," bounces it on the second "letter," then removes the letter and replaces it with the lamp. Then he laughs and points at it and says "Now it's Pxar!"
He was doing this all day with random objects - beads, wooden blocks, apple slices - and when I decided to give him a box of wooden letters, his eyes lit up and he made the word "Pixar" and did his little game a few times. Then he slowly started replacing letters. First he replaced A with D and read it (pixdr). Then I became B and he read it (pbxdr - yes, he actually pronounced that). Then X became C, P became A, and R became E - and I realized he had covertly changed "Pixar" to "ABCDE." Then he laid out the rest of the alphabet, laughing the whole time.
He is the best kid in the world and he made my whole day happy. That is all.