On the way back from visiting Hermione, who is in the hospital wing recovering from her cat-state, Harry and Ron hear Filch yelling at someone, and they round the corner to see a flood of water seeping out of Moaning Myrtle's bathroom. The boys step inside to look around, and they immediately spy a diary bobbing in the toilet. They examine it and see the name T.M. Riddle written on the first page, but the rest of the pages are blank. Ron recalls the name from his trophy-polishing detention as the boy who was rewarded for special services to the school fifty years ago. Harry feels a strange familiarity to the name, and so he pockets the diary. They show it to Hermione when she is fully cured, and she concludes that Riddle, who was commended fifty years before, must have caught the Heir of Slytherin, who had opened the Chamber of Secrets fifty years before. She tries to make words appear on the pages, but with no success.
At the beginning of February, the school is calmer; nobody else has been attacked, and the Mandrakes are becoming moody and secretive-in other words, entering adolescence-and soon will be ready to be made into an elixir. Lockhart believed that he had intimidated the monster into hiding, and by Valentine's Day he was in such a cheerful mood that he decorated the great hall in pink and organized a troupe of dwarves to deliver valentines. The dwarves were not quite so cheerful, however, and an embarrassing encounter occurs when a dwarf had to kick through the masses, knock Harry's bag out of his hands, and ultimately sit on Harry's ankles in order to deliver him a singing valentine, sent (we are fairly certain) by a nearby blushing Ginny Weasley. Once Harry has gathered his things and left the laughing crowds, he notices that all of his belongings are covered in his spilt red ink, all except Riddle's diary. This puzzles Harry, and he retires to bed early that evening and pages through the diary. He writes his name on a page and watches it disappear, and suddenly the ink rises up again, forming the words, "Hello, Harry Potter. My name is Tom Riddle. How did you come by my diary?" This begins a dialogue between the two boys with oddly similar appearances and pasts, separated by fifty years and connected through this secret diary. Riddle writes that he was in fact awarded his medal for catching the person who had opened the Chamber, and he invites Harry to visit his memory.
Harry agrees, and within seconds he is blown into the pages of the diary to the headmaster's room. Here he witnesses a conversation between Riddle and the then- headmaster in which Riddle's request to remain at Hogwarts for the summer holidays is turned down because of the recent dangers of the open Chamber of Secrets. Harry then follows Riddle through the corridors, once running into a younger, auburn-haired Dumbledore who warns Riddle to head back to his dormitory. Riddle and Harry wait in the dungeons for a long time, and finally they hear and follow nearby footsteps. The footsteps belong to a younger Hagrid, who is trying to conceal something inside a box. Riddle explains that he must turn Hagrid in for possessing the guilty monster, and Hagrid argues vehemently that the animal inside the box is innocent. Riddle pulls out his wand, casting open the box and releasing a giant, hairy spider that scuttles over him and out through the corridor. Harry is whirled back into real time, back into his dormitory, and he begins to tell Ron what he saw.
When Harry decides not to leave the diary bobbing in the toilet, we see a flash of intuition telling him that the name T.M. Riddle is significant. Voldemort left Harry with marks other than the scar on his forehead; we learn later in this book that he left him with the ability to speak Parseltongue, and in the first book of the series, we learn that the wand that chose Harry contained the brother phoenix feather to the wand that chose Voldemort. Harry is connected to his nemesis in more ways that he knows or understands, and this explains his curiosity about Riddle before he knows that Riddle is the boy who one day would become Voldemort. Good and evil are never wholly unconnected, but rather will always return to interact with each other. These moral extremes even at times share origins, as Riddle and Harry do, with their orphaned, Muggle-raised childhoods, their gift for Parselmouth, their skinny, dark-haired appearances.
The early glimpse of Riddle is telling. He is a school hero who has won his glory by framing another student, Hagrid, for the murder that he himself caused. One could go so far as to note a Satanic element in this "fall" of Riddle into Voldemort, from Hogwarts hero to the demonic figure who caused such a reign of terror among the wizard community. At the same time, a Jesus-like element resides in the younger Dumbledore, who sweeps through the halls with his auburn hair, understanding more than he lets on, yet preserving a forgiving, reticent wisdom that has not faded after fifty years. Furthermore, it is noted several times that Voldemort is threatened only by Dumbledore, because he knows that Dumbledore would never join his side.
The incident with the Valentine's Day dwarf does then amount to something beside Harry's humiliation, in that it demonstrates the ink-absorbing property of the very secret diary, inspiring Harry to experiment writing in it. We are also reminded in this incident of Ginny's long-standing crush on Harry, something that appears in certain occasions but as of yet has not taken its place in the plot.
The description of the Mandrakes touches upon another important point in the Harry Potter series. In the wizard world, everything is given the gift of life; ghosts return and "live" within the Hogwarts walls, pet owls and mice have distinct opinions and personalities of their own, dwarves, wizards, elves, cars, and plants all possess human characteristics. The Mandrakes are a particularly humorous touch, as their maturation process follows exactly the stereotypical one followed by human adolescence: first crying like babies, then becoming secretive and being ailed with acne, and eventually (when they come closer to adulthood) throwing parties and trying to move into each other's pots. The realm of magic is vibrant and curious because everything inside it has its own right to life in all its stages and eccentricities, as shown here by the Mandrakes.