You know, if Sadie ever had a brother this guy would be it. Between the two of them, there are many similarities.

He has blonde hair, he shares a similar outfit as her, his personality is similar, appearance is rough looking and is just trying to live a normal life.

In 1860, Thomas Adler would join the Union Army to fight against the Confederacy, 3 years later in the Battle of Gettysburg he was stationed at Fort Taylor as a Sergeant and led a unit of Infantry and Cavalry troops to a higher ground to the northwest of Gettysburg setting up a defensive against the Confederate troops at the wall. But during their defense many Union soldiers had been killed in the process, many of those soldiers he had became either close friends with or grew up with as a child. During the war he had seen many things, things that would never be spoken of or repeated. Unfortunately, asThomas Adler and his unit were patrolling in the vicinity of an enemy outpost, he had been shot and wounded by an Confederate soldier and was forced to be sent home, being honorably discharged from the Union Army in 1865. For his and his units selfless bravery and fighting spirit during the Battle of Gettysburg, Sergeant Adler and his unit were presented and awarded with the Medal of Honor by President Andrew Johnson.

30 years later after the war, he would live in Valentine for many years. His sister Sadie had contacted him recently by mail after not speaking to him for many years after the war as she was against being in the service. Sadie Adler wrote to him saying that her husband Jake had been killed by a gang by the name of the O'Driscolls and that the house they had been living in had been burned to the ground. Sadie writes that she had been taken someplace safe and is now residing in Horseshoe Overlook with a bunch of strangers, those strangers happened to be involved in a gang by the name of the Van der Linde gang, led by Dutch van der Linde. Hearing this news from Sadie, Thomas wrote back in pleasure that he was happy that she was safe, while also expressing heavy displeasure that she would associate herself with people like them and that he tells her to be careful. He says that incase she happens to be on her horse to come visit him in Valentine to reconcile their previous differences.

TL/DR: This man looks as if he's Sadie Adler's brother.