warned, alerted
Tom deveria ter alertado a Mary.
Tom should have warned Mary.
Se eu estivesse aqui, teria te alertado do perigo.
If I had been here, I would have warned you of the danger.
— A Pele Que Habito (2011)
Papai tinha me alertado com toda a firmeza sobre esse tipo de coisa.
Dad had warned me very firmly about this kind of thing.
Acho que eu deveria ter te alertado sobre o Tom.
I think I should have warned you about Tom.