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It does seem pretty sketchy that someone so much older than you (or someone in general) is talking to you outside of work and doing things like expecting you to answer quickly. I’d see some strong boundaries with him if you still wish to talk to him, such as letting him know not to say certain things and also not to expect replies right away. Don’t accept video calls if you don’t want to. I’d consider distancing yourself from this coworker though and trusting your gut. Sometimes we have an instinct that something isn’t right and we should follow the instinct. It doesn’t mean you’re a bad person if you communicate solely about work related things. If he continues you can go to your manager or boss so the the situation can be dealt with by an adult who is higher up. Document anything he says or does that’s sketchy and when it happens as well in case the coworker escalates.