So, my brother bought a budgie, and a week later bought a second. We'll just call them Blue and Green (both girls). He was (to my knowledge) bonded to them very well. A month or so after, my brother left for college and left the birds here. After about 2 weeks of the birds being left in the living room with no attention given to them other than food and water being refilled, I was given the responsibility of the birds, and after 2 months it feels like they still don't trust me at all.
I spend around 9 hours in a room with the cage in it, and I occasionally go up to try and feed them a treat or softly talk to them. Blue will step up onto my finger, but she won't step up outside of their cage, in fact neither will get near me at all outside of their cage. I have been able to feed them treats from my hand, and they cautiously eat bird seed out of the palm of my hand, but other than that they pretty much never get near me or my hand. They do seem more comfortable around me than my parents, but that's really not saying much. Am I doing something wrong, or do they just need more time? I try to be very patient with them and introduce new things to them very slowly, but it feels like after 2 months I've hardly made any progress.
What can I do?
If it helps to know, they get along decently. I see them preen each other, sleep together, and seem distressed if one can't find the other, but I also sometimes see Blue bullying Green.
Any advice at all is highly appreciated. Thank you.

-Quick edit, I wanted to take over for the birds for a while after my brother had gotten them. It felt like he only wanted them as a novelty after seeing some funny videos of budgies, because he paid attention to them less and less, and it had come to the point that I cared more for his birds than he did.