This story isn't of a fluent speaker, but of one who can converse in Spanish.
Mi hermano vivia un ano en Chile. Cuando el visitaba Brazil, el no comprendia un palabra. El podia.
Mi frances me da el ayuda con mi escuchar en espanol si lo hablaba lentamente. Pero, no para mi hablaba y escribia.

My brother live in Chile for a year. When he visited Brazil, he was lost, because he couldn't understand a word.

My French helps me pick up the jist of Spanish conversations. If you speak two related languages, the third one becomes easy to learn. (Not that I've learnt Spanish yet. It will be obvious to a Spanish speaker that I'd be using a dictionary to stumble my way through the Spanish part of my post. Though occassionally it 'clicks' and I can do without and make small talk).

Please feel free to correct my Spanish. Por favor esta en libertad corrigir mi espanol. IF YOU DARE! Gracias.