Oooo I have propaganda for Echo!
Echo has been shown to put his brothers above all else time and time again. While his initial relationship with the Domino Squad starts out rough, they act like true brothers by the end of that episode. When three members of the Domino Squad (his og batch) die on their first mission he is saddened. Both him and his batchmate Fives have a mini gun emblem on their armor with "for Hevy" next to it to honor one of their fallen brothers. A clone's armor is extremely important to them and their identity so it really goes to show how much Echo cared about Hevy. He gets close to the 501st captain, Rex, and develops a very strong bond with him that continues through the show and into The Bad Batch. He's later shown to miss Fives whenever he's mentioned.
Echo spends some time as a pow and is used against the Republic. He laments the idea of having been used to harm his brothers. Once he joins up with the Bad Batch he truly feels like he belongs there with them. He cares for them like he did the 501st, and loves them deeply. He's protective of his sister, Omega, as well. After the fall of the Republic he devotes himself to helping his brothers escape the Empire and live better lives. Echo mourns Tech when he dies.
All in all, Echo's entire life is centered around his brothers and his care for them. He's protective of them and fiercely loyal to them. So many of them have been taken from him (both by the Separatists and the Empire) and he doesn't want to lose more of them. Here's a quote from him. It's said after another clone says he can't possibly defeat the Empire. "It's not about that. It's about fighting for our brothers."
Thank you that's been added to the propaganda for Echo