難兄難弟

lit. hard to differentiate between elder and younger brother (idiom) / fig. one is just as bad as the other

brothers in hardship (idiom) / fellow sufferers / in the same boat

elder brother

younger brother / junior male / I (modest word in letter)

variant of 悌[ti4]

difficult (to...) / problem / difficulty / difficult / not good

disaster / distress / to scold