The phrase "be the fence" can be replaced with several synonyms based on the context. If someone needs protection or someone else's back to watch, you can use phrases such as "have someone's back," "be someone's support," or "watch someone's six." Similarly, in the context of privacy or secrecy, you can use synonyms like "keep something under wraps," "maintain confidentiality," or "preserve one's privacy." Moreover, if someone is defending or advocating for someone else, phrases like "stand up for someone," "champion a cause," or "support someone's argument" can be used. All in all, there are several synonyms available depending on the situation to replace the phrase "be the fence."".