What should you do with your reply guy?

A guy — we’ll call him David but that’s not his real name — just sent me a picture of his cat with a couple of small kittens by its side over Instagram DMs. “My cat gave birth a couple of weeks ago and had kittens,” he tells me in a reply to one of my stories, a picture of my dog. It would be fair for you to think I know this person, but I don’t. It’s just some guy who replies to absolutely everything I post, both publicly and privately, even though he never gets a response. Above his cat, who is admittedly very cute, I can see the trail of unanswered messages spanning months, maybe even a year, behind this one. I wonder if I should reply to him. He’s sent me so many messages, some of them detailed, and I’ve never replied beyond a sympathetic double-tap like here and an awkward “cheers mate!” there. Perhaps I should give him an actual response. But then I wonder if I should block him instead, because replying to everything a stranger does when you’re not getting anything back is honestly a bit weird. Having a reply guy is pretty stressful. If you’re unfamiliar with the phrase, it’s like it sounds. A guy who replies. A guy who replies all the time. The reply guy is usually a man, and a woman seems to be the usual target, and they’re a confusing phenomenon. What do the reply guys want? Are they flirting, trying to…What should you do with your reply guy?