I am afraid I don’t know the answer. I can speculate. I expect it’s a combination of the following (but insert a “probably” in each of these statements, as I don’t have empirical data):
- Some readers subscribe because they started reading a story, but only leave kudos if/when they finish the story.
- Some readers subscribe with the intention of keeping track of a story and reading it after it finishes, but never get around to reading it.
- Some readers only leave kudos on their very favorite stories.
- Some readers don’t leave kudos at all (I suspect there are many lurkers who never leave kudos, for a variety of reasons – that’s not just the case on AO3, but on most online platforms that allow any kind of interaction).
- Some readers have kinks or other interests that they don’t want to reveal to others, so they don’t leave kudos on those stories. (One option such readers may not have thought of is to leave kudos as a guest in that case, which works unless the story is locked & only available to AO3 members.)
I personally have a bunch of subscriptions to stories that finished since I subscribed, but I haven’t returned and read the end of them, so I haven’t left kudos yet. So I can vouch that that’s a thing. But other people will have to chip in and tell me if there are other reasons I haven’t thought of!
About your second question: I subscribe to fic that I know is abandoned if I’ve gone back to it at least three times, and refuse to deal with the frustration of finding it again. Or if I am emotionally unready to leave the world it created, and subscribe to leave myself a small connection. Basically, I loved it too much to let it go.
About the first: I usually do comment or give kudos, but sometimes if I’m going through an archive I’ll only do so on some of the stories, even if I love them all.
Also, sometimes my mental health is really bad, and any form of communication is beyond me. I read a lot to cope when I’m like that, but thanking the people who wrote the stories isn’t always possible.
A final reason that some people might have for subscribing but not giving kudos: they might feel that subscribing is already more of a sign of love than kudos would be. I don’t always give kudos if I’m commenting, because I assume that the comment means more. Maybe people feel the same way about subscribing and/or bookmarking?











