ともあろうOf all people, Such,

ともあろう is a grammatical structure in Japanese which highlights either the skill or responsibility that a particular person or organization has, and what they are doing despite that, or that contradicts that. It will be interpreted as ‘(A) of all people’, or ‘such as (A)’. Often, ともあろう will be followed by the speaker's opinion about how (A) is being ignorant of what is expected of them.

This construction is a combination of the case-marking particle と, the adverbial particle も, and the volitional form of the う-Verb ある, あろう ‘to be’. The literal meaning is ‘even a (B) such as (A), (C)’, with (C) being something unexpected or unwanted. ともあろう will be seen after nouns, and may be followed by the conjunction particle が ‘but’, or a combination of the noun もの and が for further emphasis.

もの is primarily used for emphasis, and other words such as 方(かた) ‘individual’, or 人(ひと) ‘person’ may also be used.

Caution

Occasionally, this grammar pattern may be used sarcastically towards someone of the same position or lower. The context of the sentence is the only thing that would clarify whether it is criticism or sarcasm.