I remember reading this short story that I hope you can help me identifying. It was a short story in a comic book, Dark Horse comics if my memory doesn't fail me.
It starts with some explorers in an alien world finding a deer-like creature with an octopus-like parasite/symbiont attached to its head. One of the explorers chases the deer, and not long after she comes back with one of these parasites attached her head too.
The story progresses with her trying to convince them that this symbiotic relation is actually a good thing (something about enhancing the senses or sharpening the mind), and that they should get an alien attached to themselves too. One by one they get caught by these creatures. The hosts also acquire a phobia of some flying creatures after getting the parasite, which later they discover is the parasite's natural predator.
The few remaining without the parasites fight to remain free, and they all get rid of the parasites when the flying creatures attack. At the end it's ambiguous whether they really had something special going on, or if their feelings were actually being manipulated by the aliens (i.e. not sure if it was a symbiosis or a parasitism), and they all leave the area in a bad mood.
Edit: clarified some points, and wanted to talk about the Dark Horse part. I think it was in a comic from Dark Horse because I remember reading HellBoy and Concrete at the time. But I didn't have a physical copy, I think I read them online, so it's possible that it's not related to Dark Horse at all. The art reminds me of Paul Chadwick's Concrete though.