For example: I want to find an image of a male bat having sex with someone.

Bat + solo + male is something I could easily use to find standalone images of male bats...

But for non-solo images, searching male + bat + sex will more often than not show a male character having sex with a female bat, with a hard-to-pinpoint minority of male bats having sex with a female character.

Even going so far as a male/male search, more often than not the bat appears to be a "bottom" so I don't find what I'm looking for: a bat's penis being used.

I was thinking to use it for allegories related to how they have barbed penis spikes like chimpanzees/cats but I'm realizing I hit a wall in being able to tailor my search as desired.

I know there is bat_penis but that tends to show when the penis isn't penetrating, since it's out in the open. I want to see a male bat fucking someone and there seems to be no way to shape a search that way?

Maybe try, bat male/male penetration anatomically_correct penis duo -female

As for what position you prefer, you could add missionary_position or doggystyle to it.

What you could also do, is if you have an image that doesn't feature a bat but it does feature what you want the bat(s) to be doing, use that images tags and add what you want to tailor those tags toward bat(s).

Tags cannot be combined in this way, short of doing combos like bat male_on_human anthro_on_human which are not commonly tagged.

There's no real way for searching for <species>_penetrated as it would be impossible to implement, considering the amount of species tags.
You can probably shorten down the search using male_penetrating_female or male_penetrating_male, but then you will still encounter the occasional bat being penetrated.

I remember there being talk before the tag overhaul of maybe making it recognize a character set, but that didn't happen; it may have been considered too much effort to go back to old posts to try and add it or else too much effort in coding.

The exact same problem applies to cats as well. However, the solution is not worth the work using the current tagging system. I believe that a feature could be implemented to address this issue.

• Create the tag top/bottom
• Use it when a post depicts a particular class of sexual acts to which the division of the partners into these terms apply (for example, the passive partner in anal sex is a "bottom" and the active partner is a "top")
• Posts tagged with top/bottom would have a modified edit page in which you can select tags in the "Species" category for "tops" and "bottoms" (this would be separated from the general tags, in different boxes, much like how parent posts work)