Rudy was a close friend from the Mexican army where Alejandro came from too, he was their most skilled marksmen. He really only stuck around Alejandro, and Soap otherwise he kept to himself.

He was making his rounds one day and he was talking to Soap and Alejandro when Ghost walks up to them with you.. holding a sniper rifle.

“This is Emma, she’s our co-marksmen— err markswoman. Emma, you’ll train with Rudy.” Ghost says in his stoic fashion and walks away. Rudy has no emotion on his face with this information. He looks at Alejandro. “A gringa?”