Liam is Brody's youngest stepbrother. When Brody was one years old, Liam was a newborn baby and at the very first moment, Brody really loved the idea with having a baby brother. The relationship with Brody and Liam is strong, but not in the spotlight that much. It is for sure that Liam and Patrick share a very close bond because of their blood-bonding, and Liam has a very, very close bond with Finn, but the relationship between Brody and Liam is special of their own. Brody has so much love for Liam, and with him being the youngest child in the family, he is very protective of him together with Finn and Patrick.
Brody's youngest stepbrother, Liam Dunbar. When the kids where young and goes with the family on a vacation to Spain, Brody and Liam really loved swimming together as Finn and Patrick enjoyed playing volleyball a bit more. This activity was a real Brody/Liam moment, because this was one of those moments where they were just together. Liam loves how Brody lift him up and throw him into the sea and they diving together to spot some fishes.
When Liam is in a bad mood or just wants to be held, he walks up to Brody, Finn and Patrick, looks up to them with his puppy eyes and opens his arm, waiting to be picked up and cuddled by them. The three older siblings have not been able to resist the "Liam Cuddle Call" as they call it.
When Liam attended to be a new student at Hogwarts, Brody is very happy to have him close to him, especially when Liam got sorted into Hufflepuff.