Originally Posted by Al-bint
I think it comes down to the fact that you are his "elder" sister so he may feel a lot of shame in telling you certain things as any young person would with their elders. You should try and get him to open up more with you. To do this you should make him feel comfortable with you and that wayt he is more likely to open up. Ask him about his interests and what he does with his day and try to make him open up more about himself and his likes, dislikes and interests etc. That way he will start to feel more comfortable with you and is more likely to open up to you.
Try not to give him the usual if you dont do this you will burn in hell lecture. But try to use wisdon and tact in your approach and try not to get angry or frustrated as guidance is not in our hands but in the hands of Allah and one is far more likely to get further by being gentle and using wisdom and tact. So try different methods and see what has more of an impact but remember not to pester him too much otherwise it will just go in one ear and come out of the other. Try to send him more reminders of death and the hereafter in particular but in different ways rather than just online lectures. If you are going to send online lectures then send him those that will inspire the young hearts like Sheikh Zahir Mahmood especially his talks about the past heros of Islam.
Also maybe a short text or e mail here and there or just a quick reminder of a hadith or ayah or read a small part of a good Islamic book sometimes when he is with you. But do not give him long lectures with him as that will not always have a positive response. Also remind him to keep good company and that those who do bad things are not true friends.
So know that guidance is not in your hands but in the hands of Allah. So you can only do your best and the rest is upto him. The main thing is to keep an Islamic atmosphere at home as much as is possible. The following thread is very beneficial in helping us to achieve this:
Is your home an Islamic home?
May Allah guide all our youth