Okay, I can see a stowaway hopping on from DS9, trying to get away from Orion Syndicate or the Gamma Quadrant. Right, I think of Quark, too.
Don't forget the Jem'Hadar "...had the ability to "shroud" themselves, a form of camouflage that acted as a personal cloaking field, effectively hiding them and their weapons from both sensors and the naked eye. (DS9: "The Jem'Hadar", "The Abandoned")"
http://memory-alpha.wikia.com/wiki/Jem'Hadar
"When they used the shroud, the immediate area in which they stood would turn dark, then become almost perfectly transparent. Only the most observant individuals could see the slight shifts in light as the Jem'Hadar moved about in their shrouded condition. (DS9: "To the Death")"
http://memory-alpha.wikia.com/wiki/Shroud
Originally, "...the ability to shroud was regulated by the presence of ketracel-white. Jem'Hadar who endured prolonged periods without the drug eventually lost their ability to shroud. Such a degeneration in their abilities signaled severe withdrawal from the addiction to ketracel-white, and indicated that death was not far off. (DS9: "Rocks and Shoals")"
http://memory-alpha.wikia.com/wiki/Shroud
This we could change, having our Cardassian/Jem'Hadar stowaway using the shroud without needing the ketracel-white anymore. Maybe he/she found a way to use the tri-nucleic fungi on Kabrel I to automatically generate ketracel-white in his/her body? Or, medically found how to wean off of it?
If the stowaway gets on from DS9, I don't want anyone to know, yet; it's too early. I'd like the stowaway to stay hidden, making a nest somewhere haha and no one know. He/she could be in the background doing whatever and the crew doesn't know, yet, but we could still write it happening.
haha thank you very much, that's really cool, I appreciate that.