Re: luka romanov
1. They were barely ever around. Even though they left him in great hands (if you can get Captain fucking America to raise your kids in your absence, you haven't fucked up that bad), it's not a substitute. Natasha and Bucky should have been around more, because their kids really aren't comfortable complaining to them at all. There's too much pressure to make the time they have together as good as possible. Luka has an easier time opening up than Steven does, but it's still complicated.
Tony just dropped the ball. He thought he was doing right by being distant, because he was afraid of being the parent his father was and messing Luka up, but in the process just ended up making Luka feel like he didn't deserve his father's attention unless he "earned" it by being "interesting" (school achievements, professional achievements, nearly dying, etc). Most of Tony's attention was material, up to and including founding an entire hospital and hiring umpteen super talented professionals when he found out Luka had heart disease as a baby, so it's... complicated. And it means that Luka doesn't actually care much about expensive gifts? He gives them because, hell, he can afford it, he'd be a dick if he didn't. But he knows firsthand, thanks to both his mom and Bucky's love and the way Cap and Carol treated him, that they're no substitute for real feelings, so Luka isn't the type to ever assign emotional weight to any material gifts he gives other people and will never use that against anybody.