Here's how a Founder responded to my cold email

Just explain how and that you thought their firm was cool and that you wanted to learn / intern for them, ect.

It is almost always a terrible idea to create a fictitious story--more so in your case, as you are interacting with the FOUNDER of a firm; not only can doing so create a situation whereby more and more lies are required, but, if found out, the trust that had been placed in you will be progressively eroded, if not immediately destroyed.

I would personally tell the guy of my finding his fund through Axial and include anything that piqued my interest. Also, don't think of any responses as being intimidating; this could definitely set you up by eventually leading to the overthinking of certain situations, such as this one. A considerable measure of boldness, supplemented (obviously) by knowledge and awareness, is unquestionably necessary in finance.  

You are overthinking it. If he replied, it's because something you said worked and he wants to communicate. Just say what you need to say plainly.