Duelling was a popular, fun amusement amongst Pure-blood Witches and Wizards such as Draco, and so the whole Summer before going back to school, as he had nothing else to do, he invited his friends over to duel with. They of course, as Pure-bloods, knew more spells than the Muggle-borns and other students at Hogwarts, due to a bit of home-schooling. But in August, he duelled too much with his friends, and was a bit tired of it. So he decided to listen in, upstairs, and with "Sonorus", he was able to hear what his Father and the Death-Eaters were saying. Of course, his Father thought he was still duelling outside with Zabini, but Zabini was there too, listening in the adults' private conversation :
"Too risky a plan." His Father was saying. "What plan?" Draco asked himself.
"But, that's the plan, Lucius, think of the pain it would cause Ginevra Weasley, the little blood traitor."
"All right, fine, so I slip it into her school supplies, and she wouldn't suspect a thing."
"The Weasleys are all too dense to suspect anything, especially that one, Ginevra Weasley."
"What if anyone else notices it?"
"Well, there won't be enough evidence to prove it."
"Right then, it's decided." Draco couldn't know what they were talking about and he disapproved of his Fathers' doings, but couldn't of course, say it out loud. Only in his heart, he could think his Father was a criminal. He forced himself to concentrate on his Father and the Death-Eaters in his home :
"And the Chamber of Secrets will be opened this year, in your son's second year."
"How do you know and why and by whom?" His Father asked the Death-Eater.
"From a very reliable source and guess who. But I can't tell you why he's doing it, probably to spread terror amongst the Muggle-Borns in Hogwarts." But Lucius was too sharp to buy it, and the Death-Eater would not say anything more.
Draco, upon hearing it, decided to alert the Golden Trio with his own House-elf and to warn Pothead, and to tell him Hogwarts wasn't going to be safe for him, nor his friends, it was the only thing he could do for them just then. After the Death-Eaters left his house and his Father out, he sent for Dobby, his own House-Elf.
"You sent for me, Master Draco?" He said, as he bowed to his young master.
"Yes, Dobby, you'll need to warn Pothead about Hogwart's not being safe anymore for him, especially for Mudbloods like Granger and blood traitors like the Weasel." But Dobby the House-Elf didn't like what his young master called them, but dared not to say it, so he said instead :
"All right. I'll do it for you, Young Master Draco."
And this was why Harry Potter, in the Summer of 1992, got a House-Elf in his Muggle relatives' house, trying to tell him to not go to Hogwarts, but as stubborn as usual, Pothead resisted Dobby's words. And Draco heard he was tried for using "the Hovering Charm" illegally in a Muggle neighbourhood. But Harry's name was cleared, as Draco knew it would be, as Dumbledore was there for him at his hearing. And this was what made the him despise the Headmaster even more, because he was always on the Golden Trio's side, no matter that they've broken 50 school rules. But in school, his Godfather and his potions master doted on him, and as he noted, he detested the Mudblood and the Gryffindor male duo just as much as he did. He, from time to time, vented his frustrations about the Golden Trio to his Godfather, in his private study in the Slytherin dungeons. But Snape was able to see through his pretences.
"Draco, you're resentful because Potter rejected your friendship yes? And you pick on Granger more often because she has better grades than you in everything, although she's a Muggle-born?" But Snape was a little daft in love matters, he didn't know his Godson had just a tiny wee bit of crush on Hermione Jean Granger, although he convinced himself, after a year of thinking of her as the "Mudblood", that he truly hated her. He in fact, mistook his crush as hate at that time of the year.
"Yes, Uncle Sev. I am hurt because Pothead chose the Mudblood and the Weasel over me."
"Don't call her that, at least, not in front of me." He thought his Uncle Sev was a little strange.
"Fine, what should I call her then?"
"Call her a Muggle-born, I understand you must call her that in your Father's presence, but I won't judge you if you shared your real thoughts about Muggle-borns like her with me." said Snape.
"Yes, Uncle Sev. I will call her a Muggle-born for your sake." But he didn't take on his Godfather's offer to share his thoughts about Muggle-borns, too afraid his Uncle Sev might let it slip one day.
But things didn't really begin for him until Gilderoy Lockhart, the newly hired DADA teacher, famous for catching dangerous monsters and such, but turned out to be an incompetent fool, founded the Duelling Club in his 2nd year and he publicly duelled Potter, his arch-nemesis, a while after School started. Everyone, including Draco, found out Pothead was a Parselmouth, during the duel, when he had summoned a snake and Pothead controlled it with Parseltongue.
As for Quidditch, the Championship began after his duel with Potter. In his first year, he couldn't compete against The-boy-who-lived because he wasn't on his House team. But this time, he begged his Father to buy the whole Slytherin team Nimbus 2001 broomsticks, the fastest ones up-to-date, so he could be his team's Seeker and could rival Pothead, the Muggle-filths' Champion, in the Wizarding sport. And of course, after their first match, he knew who cursed the Bludger who was after Scarhead, it was a Slytherin 7th year, but, as he couldn't help the Golden Trio openly because of his Father, so he kept his mouth shut about it.
"So Potter, I think this Bludger likes you."
"Someone in your House probably cursed it." said Harry to his attempt at getting a rise out of him.
"Yeah yeah, always blaming the Slytherins for the bad things that's happening in Hogwarts."
"Well, the Slytherin House does have a bad reputation." This time, it was Granger, the Mudblood.
"Mudblood, don't you dare talk to me this way. You're Muggle-filth, you've sullied my blood just by being in my presence." Hermione, he could see, was truly hurt by him and he mentally cursed himself for it. "Since when did I care about hurting her feelings?" But he had gotten so used to calling her that, and he didn't think this would affect her anymore as he always thought she was a very strong girl, but it did affect her emotionally. And so Weasley, as her champion, as always, tried to hex him by telling him to "eat slugs", but since this wasn't a known hex or jinx, it backfired on him, making him vomit slugs instead and Draco saw with glee he had to be brought to the infirmary immediately.
And much to Draco's disappointment, the Quidditch Championship just had to be cancelled off, the Chamber of Secrets had been opened. It all began with the Weasel's sister, the Weaslette, finding out about blood writings on the walls; it threatened to purge all the Muggle-borns from the School : "All the filth in Hogwarts will be cleansed", it said. She must have followed it's trail down the Chamber to know it has been opened, he thought, since she was the one who informed Hogwarts' staff about it. And everyone suspected it was Potter who did it, simply because he could speak in Parseltongue. He thought they were being absurd since he knew it was the Heir of Slytherin who did it, but just who exactly was the Heir, he didn't know, but he didn't think it could be Potter. And so, when the Pothead and the Weasel, in Crabe and Goyle's forms, were interrogating him about him being the Heir of Slytherin, he told them honestly he wasn't the Heir. But he didn't know it was Granger's idea that they drank the Polyjuice Potion, and questioned him in his friends' shapes and the latter was now in the Hospital Wing, because she used a cat's hair, instead of Millicent Bulstrode's, to make her potion.
"Do you know who it is, Draco?"
"I don't know. But they say it's Potter, how could he be, just because he could speak in Parseltongue? I mean, he's always hanging around Mudbloods and blood traitors such as Weasley and Granger." He could have reported them there and then, for breaking School Rules and such, and to get them expelled. But it wouldn't be half as fun for him, if they weren't there. So he let them go when they pretended to have stomaches and such.
"What's wrong with you two?"
"Stomache. Must go to the bathroom now."
"Must have been your muffins in the morning. I've told you often to not eat anything, Crabe." Draco went along with their excuses, knowing it was Saint Potter and Weasley.
After that incident, Draco went around boasting about how the Mudbloods would be purged from the School. But truthfully, he was just as worried about Hermione Granger as her two best friends were. Once, he told her two best male friends :
"Well, your precious little Mudblood would the first to be gone, mark my words, after all, the Monster in the Chamber feeds only on dirty Mudbloods' flesh."
"I'm afraid it would be contaminated by my blood's impurity after it fed on me." said Granger, standing up for herself. He actually liked it whenever she defended herself against his taunting, because he hated seeing her so weak. He was becoming totally addicted to baiting her now, he did that to take his mind off more serious things like his marks and such. And he still couldn't think of a any other way to get her attention. "That's not the best way, but well, what more could I do, really? As a Death-Eater's son?"
Just a few while after their little skirmish, he learned several Muggle-borns had been Petrified by the Monster in the Chambers, namely Penelope Clearwater, the Weasel's older brother's girlfriend, and his very own Mudblood : Hermione Granger. As he grew more and more worried about her, he knew he felt something for her. "But is it just a stupid crush or something deeper? No, I can't be crushing on the Mudblood, I just can't. If Father knew about this, he'd disown me straight away. And how she'd laugh at me if she knew about this!"
And then, the Weaslette had gone missing for some time too, and he had an idea about where she could be, although he wasn't about to tell Potter and Weasley. Of course, after awhile, Potter, his arch-nemesis, and the Weasel figured out on their own she was down in the Chambers, and so they rescued her from there. And later on, he learnt it was all because Potter unlocked the Chamber of Secrets with his Parselmouth abilities, and once down there, was intelligent enough to use the Basilisk's fang to destroy the Dark Lord or Riddle's diary, so it would no longer possess her and because the Headmaster of Hogwarts told the School Governors she was possessed, so she wasn't framed for the Chambers' opening and the Muggle-borns' petrification, like the Death-Eaters initially intended just a month before school started. And then he discovered the Weasel's sister had been stupidly believing all the charming lies in the diary, and when it told her to go down the Chambers, she did it because her brains got washed by Riddle's personal journal. "Her stupidity's phenomenal, the Mudblood wouldn't have fallen for this." He thought to himself one night in the Slytherin dormitory, after learning why she had gone down there from her brother, Ronald Weasley.
Some things still irked him though, like how Gryffindor won the Housecup because Pothead and the Weasel got awards and extra points for special services to the School. And everybody in the school including him knew Gilderoy Lockheart had to go to St-Mungo's because he got Obliviated by the Weasel. "But I think the Weasel deserved his points since he truly did the School a great service. And I really wonder who's the DADA teacher going to be next year."
However, his Father told him Potter freed his personal House-Elf by trickily putting a sock in Dobby's belongings when his Father tried to "Avada Kedavra" him, and this infuriated him more than Gryffindor winning the Housecup and the Inter-House Quidditch cup 2 years in row. Gryffindor won against Slytherin because of his own stupidity in the final matches, he was trying too hard to bully Potter and so got distracted by it, and that was why he let Potter catch the Snitch before him for several matches.
"Just you wait, Potter, until next year. You took what's mine. I'll take it back from you."
And this added more to their already hostile relationship. And just then, he didn't know precisely why he held such a grudge against the Weasel and he explained it by telling himself it was because he stole Saint Potter's friendship from him. If The-Boy-who-lived didn't meet him first, he reasoned with himself, he would have chosen him over the poor Ronald Weasley. But in the back of his mind, he knew it was because the redhead was too close to the Mudblood for his taste. He called her a Mudblood still, after 2 years, but he thought of it as his particular term of endearment for her, rather than a spiteful insult, though, obviously, she didn't see it his way.