Red had a really bad mindset because of Violet for a long time that they were barely a person and didn’t deserve to be happy, but when they were out on the streets still one of the things that made them want to keep living was the possibility of things getting better. When the brothers took them in along with Lilac they didn’t want to get their hopes up so they stayed distant and aggressive, hissing and snarling whenever someone got close. This stopped after a few days but they still refused to let themself be happy because they were scared that the brothers would stop being nice and treat them like a tool like Violet did back before they escaped.
It took Eclipse sitting them down and asking them how they thought of Lilac. Red said that Lilac was a good ‘bot, and that they deserved to have a happy and loving family after all the shit Violet put him through. Eclipse asks them who else deserves nice things and Red immediately responds with “You and your brothers.” Eclipse has to say, out loud, that Red also deserves to have a family, and that they’re just as much of a person as the rest of them and hugs them and telling them that he’s gonna make damn sure that they get to be happy to make up for not being there when they were alone (even though he had no control over that but that’s a heart-to-heart for later :) ).
Lilac also has issues, mostly about his self worth and how much of a person they think they are. He didn’t have a lot of autonomy and weren’t allowed to say their own opinions when they were working for Violet, so they often second guess themself and go along with whatever others say even if they don’t like or agree with them. Lunar is the one to tell them that they’re allowed to make their own choices and be their own person as he gives them a hug.
Both talks end in Lilac and Red absolutely melting into the hugs.