- Send them affordable Bitcoin on their birthday.
Give them bitcoin as a gift, but not on birthdays and valentines days and Christmas and stuff. A gift(especially for these special days I've mentioned) are mostly something to make them happy; not an opportunity for you to shove down your interests to them regardless if you have good intentions.
Unless if that person is already well-aware and have knowledge on Bitcoin and cryptocurrencies just like my sister whom I gave her $100 worth of ETH last year and a hardware wallet days after the wedding date a couple of months ago.
Although that there's nothing wrong about giving BTC as a gift, but it's better if the OP let them understand first on what Bitcoin is all about. Education is the key.