Why not dispense with all of that awkward wording and just write it like this: He and his brother do the work together. What do you think?

"He alone" means that it is only him, and nobody else is there. It is possible to say "he was alone with his brother", meaning that he was the omly person with his brother, but in the sentence you provided "he alone with his brother does the work" it is an incorrect usage. "Along with" means together with someone else, so that is the sentence you should use.

He along with his brother does the work. You could also say.. He does the work with his brother. Him and his brother do the work.

He gets along with his brother means he has good relationships with his brothers.