¿Por qué es "con" usada aquí?
Recientemente leí un cuento y tengo una pregunta acerca de algo. Algunas de las frases contienen la frase "se encontraron con (animal)". ¿Por qué es "con" usada aquí? ¿Por qué no es "se encontraron un (animal)?"

Question

Answer

It's a collocation -- words that occur together simply because "that's the way it is" (although, in some cases, there is a logic).

I think that they live here. 
Yo creo que ellos viven aquí. (lit.: I believe ...)

She is thinking about it. Ella piensa en ello (lit.: She thinks "in" it).

He calls his mother. Él llama a su madre (lit.: He calls "to" his mother) (Here, there is a logic to the collocation, use of the "personal a").

Answer

It's a collocation -- words that occur together simply because "that's the way it is" (although, in some cases, there is a logic).

I think that they live here. 
Yo creo que ellos viven aquí.  (lit.: I believe ...)

She is thinking about it. 
Ella piensa en ello (lit.:  She thinks "in" it).

He calls his mother. 
Él llama a su madre (lit.:  He calls "to" his mother) (Here, there is a logic to the collocation, use of the "personal a").