27 And the Lord said to Aaron, Go into the wilderness to meet Moses. And he went, and met him in the mount of God, and kissed him. 28 And Moses told Aaron all the words of the Lord who had sent him, and all the signs which he had commanded him.
Not only did the Lord address Moses’s insecurities by assigning Aaron as a spokesperson, but He even sent Aaron to meet Moses along the way. The path God had described to Moses was forming itself before him, and Moses would come to the Israelites ready and prepared with his brother.
We do not get much insight to the relationship between Aaron and Moses. We will learn later that Aaron was born three years before Moses, presumably before the Pharaoh’s murderous decree, and thus he was allowed to live with his family unlike Moses. Aaron would have been there as his mother weaned infant Moses and may have had memories of the time. He would have been around when his younger brother was given away to the Egyptians, and we do not know what relationship Moses had with his real family after that. And then Moses had been in exile far from Aaron, living an entire life in Midian with the family he established there.
It seems quite likely, therefore, that the two were mostly strangers to one another, knowing who the other was, but not who they really were. Even so, their reunion was still full of brotherly love and care. Aaron kissed Moses when he saw him, and this happy reunion calls to mind a very similar one between Jacob and Esau. Unlike those two, though, Aaron and Moses’s reunion was to be permanent. They would now work side-by-side for the rest of their lives. Moses informed Aaron of all the details of the Lord’s plan, and now the two shared a united in purpose.