Help with another book ID?

Cafe Society
1

I’ not even sure it’s a book. It could be a shorter-form story.

It was a western sci-fi story. It’s gotta be at least 30 or 40 years old, I read it as a teen or maybe even younger.

An alien comes to earth – maybe microbe sized, or maybe some form of energy creature. It moves into the body of a gunfighter – doesn’t take it over, but sees and hears what the guy sees and hears. It’s symbiotic --it helps him be faster in his gunfights. And for some reason I recall the phrase “(creature’s name) fashioned an ion”, which was the thing he did at key moments to kelp out his host. I’m thinking it’s vaguely Alan Dean Foster-ish, maybe written for a juvenile audience. That’s all I got.

Any ideas?

2

One bump for a rapidly fading hope…

3

My only guess would be Hal Clement’s Needle which does have a symbiotic alien inside of a human, but it isn’t a western and doesn’t feature a gunfighter, so I guess I have nothing…

4

Here’s a search engine for such stuff. I didn’t get any hits, but, I’m not very familiar with using it, either.