Now both Kaurav and Paandav started growing together, were educated together from Dronaachaarya. Duryodhan, from the beginning, was very proud, of quarreling nature, and of dominant type. While Paandav were friendly, soft spoken and kind. When Dronaachaarya was appointed their Guru, Duryodhan was always naughty, and Drone had to scold him several times; while Arjun was favorite of Drone, because he used to obey his Guru and was very attentive in his education. All this made Duryodhan more hostile towards Paandav and a kind of jealousy and enmity started in his heart towards them. 

Once in Gurukul, Dronaachaarya asked all his students to aim at a bird's eye. One by one everybody came to aim at and Dronaachaarya asked the same question to everyone of them: "What do you see?" Somebody said, "I see tree, leaves and bird.", somebody said, "I see sky, bird, its wings, its eye.", somebody said, "I see only bird." But when Arjun was called, he said - "I see only the bird's eye." Drone got very happy to get this answer and said - "Only Arjun can pierce the bird's eye." Such small events used to increase jealousy in Duryodhan's heart towards Paandav.

Their enmity grew with time under Shakuni's, Kaurav's Maamaa,  guidance. Shakuni used to live there, after his sister's marriage. Duryodhan was always busy in making evil plans to trouble Paandav especially Bheem. He had special enmity with Bheem as Bheem was very good at Gadaa and Duryodhan considered himself better than him at Gadaa. 

Several such events took place between them: On Shakuni's advice, once Duryodhn mixed poison in sweets and fed it to Bheem and threw him in the river after he was unconscious. Luckily Bheem didn't drown but went down and down and arrived in Naag Lok. Kuntee was a Naag Kanyaa so as Bheem arrived there and Naag came to know that, they welcomed him and empowered him with a great power (10,000 elephant's strength) and sent him back to shore. So Duryodhan's planning to kill him got failed, rather he had come back with extra powers.

Thus all princes grew up and became fine young men. Their education was over. Drone asked the Guru Dakshinaa from Both Kaurav and Paandav - that was to bring Drupad to him by tying him with a horse. Kaurav took their turn first as they thought that they could bring him, but when they went, they came defeated by Drupad. But when Paandav went, they brought him as Drone wanted him to be brought. Thus Paandav paid their Guru Dakshinaa, but Kaurav couldn't pay. Thus on every step Duryodhan was failing and Paandav were winning.

The type of enmity also was different with age; now the enmity was not limited to children's games, it had come to the point of kingship now. With the advice of the royal court Yudhishthir was declared as Crown Prince. Unfortunately Duryodhan himself suggested to have a competition with Yudhishthir for this selection that who should be appointed the Crown Prince, but lost it.

So once more, on the advice of Shakuni, another mischief was played to kill all Paandav. There used be an annual fair in Baaranaavat which the Crown Prince used to attend it, Raajaa himself was going there because there was no Crown Prince for some time. But recently Yudhishthir ws appointed the Crown Prince. So Vidur Jee and Bheeshm suggested that this time Yudhishthir should be sent so that people could know their would be king. Dhritraashtra had to agree for that, and he ordered to Yudhishthir to go there.

Duryodhan had some plans to burn them all there, so he encouraged Yudhishthir to take his brothers and Maa Kuntee there along with him, so that he can finish them all together. He got built a special house there - Laakshaa Grih (in Baaranaavat), through Purochan. in which he planned to burn them all, but all Paandav along with Kuntee escaped with Vidur's help even one day before. Since a family of five sons and a mother was killed in that fire, Duryodhan thought that Paandav have died along with Kuntee.  He was very happy. In that happiness he forgot to think that who set the fire in Laakshaa Grih one day before the set night. On Vidur's advice they stayed in Van for some more time to convince Dhritraashtra and Kaurav that Paandav were indeed dead, but Draupadee's Swayamvar burst out the secret and Dhritraashtra had to call them to palace.

Duryodhan had a half brother named Yuyutsu. He was never in favor of Duryodhan's actions. He tried his best to explain to Duryodhan that he should not break war with Paandav but Duryodhan woudn't listen to him, and not only him but to anybody. He was the only one among Duryodhan's relations and well wishers who fought from Paandav's side.