“被关系者”在英语中并没有一个完全固定、直接对应的单一表达，但可以根据具体语境选择合适的表述，以下几种常见表达供参考：
the one who is related to（某人/某事）：这种表达比较灵活，可根据具体语境调整。比如，“在家庭关系中，孩子通常是被关系者，受父母行为和决策的影响”可以译为“In family relationships, children are often the ones who are related to (their parents' actions and decisions), and are influenced by them.”
the party in a relationship who is affected：直接点明是在关系中受影响的一方。例如，“在商业合作中，小公司往往是被关系者，更容易受到大公司决策的冲击”可译为“In business partnerships, small companies are often the party in a relationship who is affected and more vulnerable to the impacts of large companies' decisions.”
the person/entity connected to（某人/某事）：明确指出与特定对象有关联。比如，“在案件调查中，目击者是与事件被关系者”可译为“In the case investigation, the witness is the person connected to the incident.”
the one having a connection with（某人/某事）：强调有某种联系。例如，“在社交网络中，粉丝是与偶像有某种被关系者”可译为“In social networks, fans are the ones having a connection with idols.”