Títere translates directly to "puppet". It's an evocative word that immediately brings to mind images of manipulation and lack of control.
In the context of the song, the singer uses this word to express his fear of being merely a plaything in his lover's hands, asking, "¿Dime si solo soy tu perro guardián o quizás un títere al que puedes mover al antojo de tu voluntad?" (Tell me if I'm just your guard dog or perhaps a puppet that you can move at the whim of your will?). This powerful metaphor highlights his vulnerability and the one-sided nature of the relationship, making it a memorable and emotionally charged word.
"Un Títere" is Los Rehenes' ballad about doubt curdling into accusation. The singer circles one question through both verses: does the person he's singing to actually feel what he feels, or is he just useful to them? By the chorus the question turns into an image. He isn't a partner anymore, he's a toy on a string, "Al antojo de tu voluntad" [at your every whim].
Nothing here gets resolved. The chorus just repeats, "¿Qué es lo que en verdad sientes por mí?" [What do you really feel for me?], the same way a suspicion loops in someone's head late at night, no answer arriving, just the same two lines asked again.