the whole topic is overzealously combative. Difficult to have constructive and useful conversations about.

Yes, DextertheCat, it appears that way to me also. And like most of us, I'd need months or years to study the topic and the many related topics before I could come to reasonable certainty on the issue. It's a huge rabbit hole that I don't have enough time or interest to follow; people who spent years getting medical degrees can't agree on the answer and neither can I without turning this into a full-time job. So: sorry I posted this. If there's malfeasance or error in the establishment view of viruses, I look forward to the necessary paradigm shift, but I'll watch from a distance.

What is a virus?

A mental theoretical construct, nothing more, which was at first innocently postulated to help explain causation of certain diseases. Since 1870 however, it has been the greatest fear-generating weapon ever conceived by the cabal.

What is it's purpose?

To frighten the gullible masses

Why do they exist?

They don't. Just read their explanation of what they CLAIM they are. Zero sense can be made of them if one is willing to rise above a lifetime of brainwashing, which isn't always easy granted...

Is it some type of population control device?

If by "It" we can agree on the "mental construct" alone, I would answer "yes" to this (see my comment below this one as someone asked a similar question I elaborated on more fully.

If so, what dictates the appearance of a virus? How or what is the mechanism of creation?

That's a darn good question. If you consider my assessment, you'll find the "Occam's razor" answer is quite easy to arrive at.

Why is virology so difficult to study?

Because it's a pseudoscientific endeavor held up by dozens of lies, which is why they cannot perform even the most basic steps of the SCIENTIFIC METHOD (read my long comment above this one for more clarity).

they aren't alive, but they aren't not alive.

Exactly. Does this make any sense? Imagine you're 10-years old and you'll find the correct answer almost every time, prior to your education (brainwashing) in which you were instructed billions of times to "trust the experts". Had you told your 5th grade teacher that "viruses don't make sense" loudly enough, you would have been scolded, punished or received a lower grade on a test to teach you to never question the authorities again! It took me the better part of my middle school years to realize this was happening and that if I wanted good grades I better "go along to get along".

The entire debate is difficult to grasp.

There really isn't any debate to be had. That's why Steve backed out of his original offer to have a friendly discussion. The first part of someone making a CLAIM, is that they have the burden of PROOF on their shoulders. And yet to date, none has been proffered. Instead, they change the meanings of words we all understand, like "Isolation" to hide their deception. Or with their modern "virus detection software", they deceptively claim they are doing "Gene SEQUENCING", which means to take a FULLY INTACT GENE SEQUENCE, of say a carrot, or a mouse, or a human for example, and then snipping it up into different pieces to study it. But there's one GIANT EXCEPTION in the "gene sequencing" realm that they do their best to obfuscate. And wouldn't you know, it happens to be when they work with fake viruses. Instead of what they do for every other organism on the planet, with viruses they actually do "Gene ASSEMBLING", as they are never able to find a fully intact "viral genome sequence" no matter where they look. So their deception in this process is by finding itty bitty broken down snippets of RNA in their fluid/tissue samples which don't match up to "Known organism genetic sequences" (like a carrot, mouse, human, etc.).....obviously because they're just tiny fragments of a decayed cell (a HUMAN CELL). So what they do for "viruses" is literally STITCH these RNA fragments "of unknown origin" together into patchwork "in silico" (computer generated) sequences and call them "viruses". How's that for ultra-slick deception? They are ASSEMBLING hypothetical creatures, never found in nature, out of thin air and calling them viruses!

Why can viruses infect one person, but another in close contact is immune. Strength of immune system?

You're not going to like this answer. Nobody ever does. But here goes. There's no such thing as the "immune system". The corrupt medical establishment made it up in 1972 (the first appearance of such a thing in any medical textbook) by hijacking the lymphatic (garbage collection) system and making up a bunch of phony "killer T-Cells" and such. It's all a lie. There is nothing to be "immune" to in the first place, so naturally there would be no need for an "immune system". And to be clear, if something that doesn't belong within the sterile environment of your body, your body will do everything possible to remove it, like a splinter, piece of glass, bullet, poison from a jab, etc. But this doesn't have anything to do with "immunity". This is simply protection.

Why are fragments of DNA found, but not a complete whole DNA sequence?

They have no rational answer to this question, because it's all a lie.

If they have macrovirus structures, like in the pictures, why don't we have a complete DNA structure?

As the saying goes, "pictures are worth a thousand words" but have zero validity in SCIENCE, eh?

Is the lack of a complete DNA sequence untrue?

If your question is, can they find a "complete DNA (or RNA) sequence" IN THE WILD, IN NATURE, then yes, they completely LACK even a modicum of proof of such. They can only MANUFACTURE fake "viruses" through the poisoning of monkey kidney cells (where they get their pictures) or via the Gene ASSEMBLY method.

I would like to understand, but the whole topic is overzealously combative. Difficult to have constructive and useful conversations about.

I'm happy to answer any and all of your questions. I've become a bit of a "non-mainstream expert" on the topic these past 3 years. The reason for the combativeness is because the establishment is fighting to maintain their 150-year HIGHLY PROFITABLE deception. They literally can't answer even the most basic questions, so they ATTACK instead. It's a sad state of affairs, but this is clearly the reason (see my above comment list of questions they won't/can't answer for starters).

Keep your mind open. This isn't something you unwind overnight. Keep asking questions and you'll arrive at the correct conclusion!