Why was Shaitan created?

Why did Allah create shaitan nida api (api : sister) ? Was the question my younger brother asked me, his question made me realise, that this 10 year old kid is now slowly making entry into the "real world". The question was not easy to answer, the biggest challenge was to make Araf understand the real meaning of what shaitan is, of what Allah is, of what insaan is and of what world is.
Because, I was happy about this thought which erupted like a volcano in my brother's mind!
Well, this is what I told him,
God, made man, for him he made woman, he made them perfect, placed them in the jannat (heaven), provided them with all the luxuries, ordered them for just one thing, and that was to obey Allah and not listen to Iblis ( shaitan), (Iblis was an  angel, he is a believer of Allah, but he disobeyed the almighty, he did not bow infront of adam , when Allah asked all the angels to do so. And since then he said to God, that I will make your creation : referring to Adam, disobey you)
Allah, ordered Adam not to eat the apple of that tree, in the jannat, and not listen to Iblis, things did not happen that way, and Allah as a punishment decided to send Adam and Eve along with Shaitan to this world.
Then, Shaitan, told Allah that he will till the last day of judgement , keep making his creation disobey him.
Allah blessed us, with Brain, which provided us with a power of distinguishing between the right and the wrong, he gave us the ability to stay away from shaitan, and then said to the mankind, that I have blessed you with the ability to think, now it is on you, that you stay away from shaitan or not,
If you wish to return to the jannat, from where you have come in this world, you will have to obey me.
So now, it is on you Araf, if you listen to the shaitan, and do what he makes you do, or you stay strong, keep your nerves right, and obey the almighty, and this on the day of qayamat will decide, whether you go to the jahannum (hell) following the shaitan, or you go to the place from where you have come.
This life is an exam, you have to pass it, and earn your reward.
The exam is easy, if you follow the path of Allah,
It will be the easiest if you follow the path of shaitan, but remember, if you follow Shaitan's path, you will have to follow him, on the last day of judgement too.
Its you who has to decide. I know you will make a clever choice.