There are several synonyms for the phrase "are one's tail." Some possible options include "are one's shadow," "are one's constant companion," "are always following," or simply "are always present." These phrases all convey the idea of something or someone being closely connected to or following another entity. Depending on the context in which the phrase is used, different synonyms may be more appropriate than others. For example, "are always present" might be a good choice for describing a persistent feeling or thought that someone experiences, while "are one's shadow" might be a better fit for describing someone who always seems to be following another person around.
