Why did Draco do it?

[Julia]

No: HPFGUIDX 125305


I've just reread a few first chapters of PS/SS and there is one 
think I can't stop thinking about.

Why did Malfoy then, in the train, came into Harry's compartment? He 
didn't do it just to take a look at Potter but he intended to have 
him on his side. What for?
I can't think of any good explanation... Did Lucius tell him to do 
this? or he was just curious?

It doesn't make sense because he had to know that first, Harry isn't 
a pureblood, second, he is certainly not on the evil side, third, 
how would Harry be useful for Draco?
I know that probably it wasn't good to be openly against Harry and 
that Lucius probably told Draco to pretend that he has nothing 
against Potter. But it still doesn't obligate him to make friends 
with Potter - everybody knows that the Malfoys isn't a welcoming, 
nice family - it wouldn't be suspicious if Draco would just ignore 
Potter. And he actually wants to shake hand with him - it wasn't 
just a formal think that he HAD to do because dad told him to 
behave...
He actually wants Harry to be on his side! He is nice to him and he 
introduces his goons... He didn't have to do THAT! Even Snape didn't 
do this!

I'm wondering now why Draco did it... was it because Lucius told him 
to do this (and if yes then why - what was the purpose of having 
Potter on their side???) or he just thought it would be nice to have 
a famous person beside him?? (but then again - everybody knows that 
they are on different sides - it's not the secret - at least Snape 
doesn't make any secret of it...)
What do you think about it? Can anybody explain it to me?


this is the quote btw:
Three boys entered, and Harry recognized the middle one at once: it 
was the pale boy from Madam Malkin's robe shop. 
He was looking at Harry with a lot more interest than he'd shown 
back in Diagon Alley.  
"Is it true?" he said. "They're saying all down the train that Harry 
Potter's in this compartment. So it's you, is it?"  
"Yes," said Harry. He was looking at the other boys. Both of them 
were thickset and looked extremely mean. Standing on either side of 
the pale boy, they looked like bodyguards.  
"Oh, this is Crabbe and this is Goyle," said the pale boy 
carelessly, noticing where Harry was looking. "And my name's Malfoy, 
Draco Malfoy."  
Ron gave a slight cough, which might have been hiding a snigget. 
Draco Malfoy looked at him.  
"Think my name's funny, do you? No need to ask who you are. My 
father told me all the Weasleys have red hair, freckles, and more 
children than they can afford."  
He turned back to Harry. "You'll soon find out some wizarding 
families are much better than others, Potter. You don't want to go 
making friends with the wrong sort. I can help you there."  
He held out his hand to shake Harry's, but Harry didn't take it.  
"I think I can tell who the wrong sort are for myself, thanks," he 
said coolly.  
Draco Malfoy didn't go red, but a pink tinge appeared in his pale 
cheeks.  
"I'd be careful if I were you, Potter," he said slowly. "Unless 
you're a bit politer you'll go the same way as your parents. They 
didn't know what was good for them, either. You hang around with 
riffraff like the Weasleys and that Hagrid, and it'll rub off on 
you." 

Julia who is now really confused about the purpose of this 
encounter...