I think the problem isn't the Miriam , but the stories with her. The best one is that with stella the no escape and the perils. The others are too bad. The problem isn't Miriam , but blackaaders inspiration
I agree that Perils, No escape and the recent one with Stella were good, but I'm going out on a limb here and guessing that Perils did not sell well. Perils had 1 female lead and 6 monsters, which was a record at the time, still is, for number of characters, more than 2nd place (at the time) which was 1 female 3 monsters (Now 2nd place I think is 2 female leads 3 monsters). This probably made it longer to render/make poses for. I think that is why it only had 25 images, about half of his normal story lengths, yet he sold for the normal price of other stories with 50 images. I quite frankly like Perils, especially with all the free images I collected and just in general its a good image set. To an actual paying customer, however, I can see why they'd shy away from buying perils since it's priced the same as other image galleries but has half the images.
I disagree with your assessment that her other galleries are bad. The Gym and Behind Bars were very good sets, albeit there were no elements of monster rape, which I know is a major selling point for Blackadder's works. If that is a requirement for you to enjoy Blackadder's works, Monster Sex 3, Gallery 2, and Bru 1 + 2 were pretty good if that's what you're looking for. She also has the most free galleries that are really good, Magic Show 1, Feeding Time, and all the free Perils artwork I was speaking of.
There is some work of Miriam I'm not a fan of, but that's true for all his leads. Sometimes I get sick of Gisela's sets, I remember when After Midnight was dropped out of the blue, I didn't really like it because it felt as though we've seen all this before, and there wasn't anything new being delivered.
In my opinion, here's how Miriam's sets sold in the order that they were released:
1. Monster Sex 3 sold well because they were part of his very popular Monster Sex series and was her debut
2. The Gym sold poorly because lack of monster rape
3. Behind Bars same reason as above
4. No Escape sold well, probably the best Miriam gallery
5. Perils sold poorly for lack of images
Perils was the last set before he decided to put Miriam on hiatus until Gallery 1. If he actually made this decision on this set, then that would be a huge mistake, because of what I explained earlier. If The Gym/Behind Bars did sell poorly due to my theory of lack of monster rape, then other image sets with other leads should've done the same and Blackadder should've realized that it wasn't Miriam, but the content (or lack thereof) of the gallery.
Once again, this is all speculation. The only person who knows how the sets actually sold are Blackadder and Renderotica. The only person who knows how Blackadder reached the decision to stop doing Miriam is, well, Blackadder. Maybe all her sets sold poorly, or poor in comparison to other leads. Maybe none of them sold poorly and he just wanted an excuse to stop doing Miriam.