to face the music
A fixed idiom built on atenerse a, equivalent to English 'to face the music' or 'to take the consequences' — it's a warning that someone will have to accept whatever follows from their own actions: si haces eso, atente a las consecuencias.
Treating this as a separate verb to memorize — it's just atenerse a conjugated with 'las consecuencias' as the object; once you know atenerse a, this phrase needs no extra grammar.
Often confused with atener.
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"atenerse a las consecuencias" means "to face the music".